Dataset Information

Aquaporin 4-specific T cells in neuromyelitis optica exhibit a Th17 bias and recognize Clostridium ABC transporter.

ABSTRACT:

Objective

Aquaporin 4 (AQP4)-specific autoantibodies in neuromyelitis optica (NMO) are immunoglobulin (Ig)G1, a T cell-dependent Ig subclass, indicating that AQP4-specific T cells participate in NMO pathogenesis. Our goal was to identify and characterize AQP4-specific T cells in NMO patients and healthy controls (HC).

Methods

Peripheral blood T cells from NMO patients and HC were examined for recognition of AQP4 and production of proinflammatory cytokines. Monocytes were evaluated for production of T cell-polarizing cytokines and expression of costimulatory molecules.

Results

T cells from NMO patients and HC proliferated to intact AQP4 or AQP4 peptides (p11-30, p21-40, p61-80, p131-150, p156-170, p211-230, and p261-280). T cells from NMO patients demonstrated greater proliferation to AQP4 than those from HC, and responded most vigorously to p61-80, a naturally processed immunodominant determinant of intact AQP4. T cells were CD4(+), and corresponding to association of NMO with human leukocyte antigen (HLA)-DRB1*0301 and DRB3, AQP4 p61-80-specific T cells were HLA-DR restricted. The T-cell epitope within AQP4 p61-80 was mapped to 63-76, which contains 10 residues with 90% homology to a sequence within Clostridium perfringens adenosine triphosphate-binding cassette (ABC) transporter permease. T cells from NMO patients proliferated to this homologous bacterial sequence, and cross-reactivity between it and self-AQP4 was observed, supporting molecular mimicry. In NMO, AQP4 p61-80-specific T cells exhibited Th17 polarization, and furthermore, monocytes produced more interleukin 6, a Th17-polarizing cytokine, and expressed elevated CD40 and CD80 costimulatory molecules, suggesting innate immunologic dysfunction.

Interpretation

AQP4-specific T-cell responses are amplified in NMO, exhibit a Th17 bias, and display cross-reactivity to a protein of an indigenous intestinal bacterium, providing new perspectives for investigating NMO pathogenesis.

SUBMITTER: Varrin-Doyer M

PROVIDER: S-EPMC3405197 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Objective Neuromyelitis optica and its spectrum disorders (NMOSD) are inflammatory demyelinating diseases (IDD) with a specific biomarker, aquaporin-4-IgG. Prior NMO/NMOSD epidemiological studies are limited by lack of aquaporin-4-IgG seroprevalence assessment, absence of population-based USA studies and under-representation of blacks. To overcome these limitations, we sought to compare NMO/NMOSD seroepidemiology across two ethnically divergent populations. Methods We performed a population-based comparative study of the incidence (2003-2011) and prevalence (on December 31, 2011) of NMO/NMOSD and aquaporin-4-IgG seroincidence and seroprevalence (sera collected in 80-84% of IDD) among patients with IDD diagnosis in Olmsted County, USA (82% white [Caucasian]) and Martinique (90% black [Afro-Caribbean]). Aquaporin-4-IgG was measured by M1-isoform-fluorescent-activated-cell-sorting assays. Results The age and sex adjusted incidence (7.3 vs 0.7/1,000,000 person-years [p<0.01]) and prevalence (10 vs 3.9/100,000[p=0.01]) in Martinique exceeded that in Olmsted County. The AQP4-IgG age and sex-adjusted seroincidence (6.5 vs 0.7/1,000,000 person-years [p<0.01]) and seroprevalence (7.9 vs 3.3/100,000[p=0.04]) were also higher in Martinique than Olmsted County. The ethnicity-specific prevalence was similar in Martinique and Olmsted County: 11.5 and 13/100,000 in blacks, and 6.1 and 4.0/100,000 in whites, respectively. NMO/NMOSD represented a higher proportion of IDD in Martinique than Olmsted County (16% vs 1.4%; p<0.01). The onset age (median, 35-37 years) and female:male distribution (8-9:1) were similar across both populations; 60% of prevalent cases were either blind in one eye, dependent on a gait aid or both. Interpretation This study reports the highest prevalence of NMO/NMOSD in any population (10/100,000 in Martinique), estimates it affects 16,000-17,000 in the USA (higher than previous predictions) and demonstrates it disproportionately affects blacks. This article is protected by copyright. All rights reserved.