Semiquantitative measurement of aquaporin-4 antibodies as a possible surrogate marker of neuromyelitis optica spectrum disorders with systemic autoimmune diseases

Neuromyelitis optica spectrum disorders with and without associated autoimmune diseases

OBJECTIVES

We aimed to determinate the frequency of this association and compare the features of neuromyelitis optica spectrum disorder (NMOSD) with and without associated autoimmune diseases (AD) in a Latin American (LATAM) population in clinical practice.

METHODS

We retrospectively reviewed the medical records of patients with NMOSD according to the 2015 diagnostic criteria. Patients from Argentina (n=77), Brazil (n=46), and Venezuela (n=17) were enrolled and classified into two groups as follows: with AD or without AD. Clinical, paraclinical (including aquaporin-4 antibodies (AQP4-ab) status), magnetic resonance imaging (MRI), and prognosis data were analyzed and compared. Kaplan-Meier (KM) and the Nelson-Aalen estimator analyses were performed to estimate both time and the cumulative hazard risk of disability reaching an EDSS≥4; and time for the first recurrence.

RESULTS

Out of 140 patients, 33 (23.5%) patients had associated an AD at presentation. The most frequent associated AD was Hashimoto disease (n=10) followed by lupus (n=7) and Sjogren's syndrome (n=6). However, rituximab use (42.4% vs. 21.5%, p=0.02), female gender (82.2% vs. 100%, p=0.006), corticospinal lesions on MRI (0% vs. 12.5%, p=0.01) at onset, and positivity for antinuclear antibodies (21.2% vs. 48.4%, p=0.03) were significantly associated with NMOSD patients with AD in comparison to NMOSD patients without AD. No differences were found in other clinical and paraclinical aspects between groups. KM and Nelson-Aalen estimator analyses did not show differences between groups.

CONCLUSION

NMOSD patients associated with AD were observed in 23.5%. In addition, NMOSD patients with and without associated AD were similar in most evaluated features.

[Comorbidity of neuromyelitis optica spectrum disorder and systemic lupus erythematosus]

The comorbidity of neuromyelitis optica spectrum disorder (NMOSD) and systemic lupus erythematosus (SLE) is a poorly studied problem. The issues of the pathogenetic relationship between these diseases, timely diagnosis of their co-existence in one patient, disease course and therapeutic approaches are the most relevant. The authors summarize current views on the state of the problem and analyze three clinical cases of NMOSD and SLE comorbidity including the diagnostic issues and therapeutic approaches.

Aquaporin-4 antibodies (NMO-IgG) as a serological marker of neuromyelitis optica: a critical review of the literature

Antibodies to aquaporin-4 (called NMO-IgG or AQP4-Ab) constitute a sensitive and highly specific serum marker of neuromyelitis optica (NMO) that can facilitate the differential diagnosis of NMO and classic multiple sclerosis. NMO-IgG/AQP4-Ab seropositive status has also important prognostic and therapeutic implications in patients with isolated longitudinally extensive myelitis (LETM) or optic neuritis (ON). In this article, we comprehensively review and critically appraise the existing literature on NMO-IgG/AQP4-Ab testing. All available immunoassays-including tissue-based (IHC), cell-based (ICC, FACS) and protein-based (RIPA, FIPA, ELISA, Western blotting) assays-and their differential advantages and disadvantages are discussed. Estimates for sensitivity, specificity, and positive and negative likelihood ratios are calculated for all published studies and accuracies of the various immunoassay techniques compared. Subgroup analyses are provided for NMO, LETM and ON, for relapsing vs. monophasic disease, and for various control groups (eg, MS vs. other controls). Numerous aspects of NMO-IgG/AQP4-Ab testing relevant for clinicians (eg, impact of antibody titers and longitudinal testing, indications for repeat testing, relevance of CSF testing and subclass analysis, NMO-IgG/AQP4-Ab in patients with rheumatic diseases) as well as technical aspects (eg, AQP4-M1 vs. AQP4-M23-based assays, intact AQP4 vs. peptide substrates, effect of storage conditions and freeze/thaw cycles) and pitfalls are discussed. Finally, recommendations for the clinical application of NMO-IgG/AQP4-Ab serology are given.

Aquaporin-4 antibodies (NMO-IgG) as a serological marker of neuromyelitis optica: a critical review of the literature

Antibodies to aquaporin-4 (called NMO-IgG or AQP4-Ab) constitute a sensitive and highly specific serum marker of neuromyelitis optica (NMO) that can facilitate the differential diagnosis of NMO and classic multiple sclerosis. NMO-IgG/AQP4-Ab seropositive status has also important prognostic and therapeutic implications in patients with isolated longitudinally extensive myelitis (LETM) or optic neuritis (ON). In this article, we comprehensively review and critically appraise the existing literature on NMO-IgG/AQP4-Ab testing. All available immunoassays-including tissue-based (IHC), cell-based (ICC, FACS) and protein-based (RIPA, FIPA, ELISA, Western blotting) assays-and their differential advantages and disadvantages are discussed. Estimates for sensitivity, specificity, and positive and negative likelihood ratios are calculated for all published studies and accuracies of the various immunoassay techniques compared. Subgroup analyses are provided for NMO, LETM and ON, for relapsing vs. monophasic disease, and for various control groups (eg, MS vs. other controls). Numerous aspects of NMO-IgG/AQP4-Ab testing relevant for clinicians (eg, impact of antibody titers and longitudinal testing, indications for repeat testing, relevance of CSF testing and subclass analysis, NMO-IgG/AQP4-Ab in patients with rheumatic diseases) as well as technical aspects (eg, AQP4-M1 vs. AQP4-M23-based assays, intact AQP4 vs. peptide substrates, effect of storage conditions and freeze/thaw cycles) and pitfalls are discussed. Finally, recommendations for the clinical application of NMO-IgG/AQP4-Ab serology are given.