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Patterns of antibody binding to aquaporin-4 isoforms in neuromyelitis optica.

Mader S, Lutterotti A, Di Pauli F, Kuenz B, Schanda K, Aboul-Enein F, Khalil M, Storch MK, Jarius S, Kristoferitsch W, Berger T, Reindl M - PLoS ONE (2010)

Bottom Line: In contrast, IgM anti-AQP4 Abs were not only found in some NMO and high risk patients, but also in controls.Our results confirm M-23 AQP4-IgG Abs as reliable biomarkers in patients with NMO and high risk syndromes.M-1 and M-23 AQP4-IgG Abs are significantly associated with a higher number of relapses and longer disease duration.

View Article: PubMed Central - PubMed

Affiliation: Clinical Department of Neurology, Innsbruck Medical University, Innsbruck, Austria.

ABSTRACT

Background: Neuromyelitis optica (NMO), a severe demyelinating disease, represents itself with optic neuritis and longitudinally extensive transverse myelitis. Serum NMO-IgG autoantibodies (Abs), a specific finding in NMO patients, target the water channel protein aquaporin-4 (AQP4), which is expressed as a long (M-1) or a short (M-23) isoform.

Methodology/principal findings: The aim of this study was to analyze serum samples from patients with NMO and controls for the presence and epitope specificity of IgG and IgM anti-AQP4 Abs using an immunofluorescence assay with HEK293 cells expressing M-1 or M-23 human AQP4. We included 56 patients with definite NMO (n = 30) and high risk NMO (n = 26), 101 patients with multiple sclerosis, 27 patients with clinically isolated syndromes (CIS), 30 patients with systemic lupus erythematosus (SLE) or Sjögren's syndrome, 29 patients with other neurological diseases and 47 healthy controls. Serum anti-AQP4 M-23 IgG Abs were specifically detected in 29 NMO patients, 17 patients with high risk NMO and two patients with myelitis due to demyelination (CIS) and SLE. In contrast, IgM anti-AQP4 Abs were not only found in some NMO and high risk patients, but also in controls. The sensitivity of the M-23 AQP4 IgG assay was 97% for NMO and 65% for high risk NMO, with a specificity of 100% compared to the controls. Sensitivity with M-1 AQP4 transfected cells was lower for NMO (70%) and high risk NMO (39%). The conformational epitopes of M-23 AQP4 are the primary targets of NMO-IgG Abs, whereas M-1 AQP4 Abs are developed with increasing disease duration and number of relapses.

Conclusions: Our results confirm M-23 AQP4-IgG Abs as reliable biomarkers in patients with NMO and high risk syndromes. M-1 and M-23 AQP4-IgG Abs are significantly associated with a higher number of relapses and longer disease duration.

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NMO-IgG staining patterns in AQP4-EmGFP versus AQP4 expressing cells.Fusion of EmGFP to AQP4 molecules has no effect on the formation of the different staining patterns of NMO-IgG in M-1 and M-23 AQP4 transfected cells. NMO-IgG has the same laminar staining pattern when binding M-23 AQP4 with and without EmGFP fusion (A). In contrast, cells transfected with M-1 AQP4-EmGFP and M-1 AQP4 have a more point shaped staining pattern (B).
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pone-0010455-g002: NMO-IgG staining patterns in AQP4-EmGFP versus AQP4 expressing cells.Fusion of EmGFP to AQP4 molecules has no effect on the formation of the different staining patterns of NMO-IgG in M-1 and M-23 AQP4 transfected cells. NMO-IgG has the same laminar staining pattern when binding M-23 AQP4 with and without EmGFP fusion (A). In contrast, cells transfected with M-1 AQP4-EmGFP and M-1 AQP4 have a more point shaped staining pattern (B).

Mentions: In order to exclude that EmGFP might influence the formation of large arrays compared to the non-fused AQP4 proteins we have also over-expressed M-1 and M-23 proteins without EmGFP. We observed the same NMO-IgG binding patterns using M-1 and M-23 AQP4 transfected cells without the EmGFP fusion protein, as illustrated in Figure 2. Consequently we can exclude that EmGFP has an influence on the formation of OAPs. Furthermore, EmGFP fused versus unfused AQP4 M-1 and M-23 transfected cells gave identical results in a subset of 15 M-1 and M-23 seropositive and 15 M-1 and M-23 seronegative patients.


Patterns of antibody binding to aquaporin-4 isoforms in neuromyelitis optica.

Mader S, Lutterotti A, Di Pauli F, Kuenz B, Schanda K, Aboul-Enein F, Khalil M, Storch MK, Jarius S, Kristoferitsch W, Berger T, Reindl M - PLoS ONE (2010)

NMO-IgG staining patterns in AQP4-EmGFP versus AQP4 expressing cells.Fusion of EmGFP to AQP4 molecules has no effect on the formation of the different staining patterns of NMO-IgG in M-1 and M-23 AQP4 transfected cells. NMO-IgG has the same laminar staining pattern when binding M-23 AQP4 with and without EmGFP fusion (A). In contrast, cells transfected with M-1 AQP4-EmGFP and M-1 AQP4 have a more point shaped staining pattern (B).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2864757&req=5

pone-0010455-g002: NMO-IgG staining patterns in AQP4-EmGFP versus AQP4 expressing cells.Fusion of EmGFP to AQP4 molecules has no effect on the formation of the different staining patterns of NMO-IgG in M-1 and M-23 AQP4 transfected cells. NMO-IgG has the same laminar staining pattern when binding M-23 AQP4 with and without EmGFP fusion (A). In contrast, cells transfected with M-1 AQP4-EmGFP and M-1 AQP4 have a more point shaped staining pattern (B).
Mentions: In order to exclude that EmGFP might influence the formation of large arrays compared to the non-fused AQP4 proteins we have also over-expressed M-1 and M-23 proteins without EmGFP. We observed the same NMO-IgG binding patterns using M-1 and M-23 AQP4 transfected cells without the EmGFP fusion protein, as illustrated in Figure 2. Consequently we can exclude that EmGFP has an influence on the formation of OAPs. Furthermore, EmGFP fused versus unfused AQP4 M-1 and M-23 transfected cells gave identical results in a subset of 15 M-1 and M-23 seropositive and 15 M-1 and M-23 seronegative patients.

Bottom Line: In contrast, IgM anti-AQP4 Abs were not only found in some NMO and high risk patients, but also in controls.Our results confirm M-23 AQP4-IgG Abs as reliable biomarkers in patients with NMO and high risk syndromes.M-1 and M-23 AQP4-IgG Abs are significantly associated with a higher number of relapses and longer disease duration.

View Article: PubMed Central - PubMed

Affiliation: Clinical Department of Neurology, Innsbruck Medical University, Innsbruck, Austria.

ABSTRACT

Background: Neuromyelitis optica (NMO), a severe demyelinating disease, represents itself with optic neuritis and longitudinally extensive transverse myelitis. Serum NMO-IgG autoantibodies (Abs), a specific finding in NMO patients, target the water channel protein aquaporin-4 (AQP4), which is expressed as a long (M-1) or a short (M-23) isoform.

Methodology/principal findings: The aim of this study was to analyze serum samples from patients with NMO and controls for the presence and epitope specificity of IgG and IgM anti-AQP4 Abs using an immunofluorescence assay with HEK293 cells expressing M-1 or M-23 human AQP4. We included 56 patients with definite NMO (n = 30) and high risk NMO (n = 26), 101 patients with multiple sclerosis, 27 patients with clinically isolated syndromes (CIS), 30 patients with systemic lupus erythematosus (SLE) or Sjögren's syndrome, 29 patients with other neurological diseases and 47 healthy controls. Serum anti-AQP4 M-23 IgG Abs were specifically detected in 29 NMO patients, 17 patients with high risk NMO and two patients with myelitis due to demyelination (CIS) and SLE. In contrast, IgM anti-AQP4 Abs were not only found in some NMO and high risk patients, but also in controls. The sensitivity of the M-23 AQP4 IgG assay was 97% for NMO and 65% for high risk NMO, with a specificity of 100% compared to the controls. Sensitivity with M-1 AQP4 transfected cells was lower for NMO (70%) and high risk NMO (39%). The conformational epitopes of M-23 AQP4 are the primary targets of NMO-IgG Abs, whereas M-1 AQP4 Abs are developed with increasing disease duration and number of relapses.

Conclusions: Our results confirm M-23 AQP4-IgG Abs as reliable biomarkers in patients with NMO and high risk syndromes. M-1 and M-23 AQP4-IgG Abs are significantly associated with a higher number of relapses and longer disease duration.

Show MeSH
Related in: MedlinePlus