Increased T-cell immunity against aquaporin-4 and proteolipid protein in neuromyelitis optica.

In neuromyelitis optica (NMO), B-cell autoimmunity to aquaporin-4 (AQP4) has been shown to be essential. However, the role of T cells remains ambiguous. Here, we first showed an increase in CD69+ activated T cells in PBMCs during NMO relapses. Next, T-cell responses to AQP4 and myelin peptides were studied in 12 NM0 patients, 10 multiple sclerosis (MS) patients and 10 healthy subjects (HS). Four hours after adding 1 of 28 overlapping AQP4 peptides, a mixture of AQP4 peptides (AQP4-M) or one of six distinct myelin peptides to 2-day cultured PBMC, CD69 expression on CD4+ T cells was examined. Data were analyzed by paired t-test, frequency of samples with 3-fold increase of CD69 on CD4+ cells (fSI3) and mean stimulation index (mSI). The T-cell response to AQP4-M was significantly increased in NMO (fSI3 = 10/12, mSI = 5.50), with AQP4 (11-30) and AQP4 (91-110) representing the two major epitopes (AQP4 (11-30), fSI3 = 11/12, mSI = 16.0 and AQP4 (91-110), fSI3 = 11/12, mSI = 13.0). Significant but less extensive responses to these two epitopes were also observed in MS and HS. Significant reactivities against AQP4 (21-40), AQP4 (61-80), AQP4 (101-120), AQP4 (171-190) and AQP4 (211-230) were exclusively found in NMO. In addition, responses to AQP4 (81-100) were higher and more frequently detected in NMO, without reaching statistical significance. Interestingly, among the six myelin peptides studied, proteolipid protein (95-116) induced a significant T-cell response in NMO (fSI3 = 7/12, mSI = 4.60). Our study suggests that cellular as well as humoral responses to AQP4 are necessary for NMO development and that the immune response to myelin protein may contribute to disease pathogenesis.

T cell gene expression profiling identifies distinct subgroups of Japanese multiple sclerosis patients.

To clarify the molecular background underlying the heterogeneity of multiple sclerosis (MS), we characterized the gene expression profile of peripheral blood CD3+ T cells isolated from MS and healthy control (CN) subjects by using a cDNA microarray. Among 1258 cDNAs on the array, 286 genes were expressed differentially between 72 untreated Japanese MS patients and 22 age- and sex-matched CN subjects. When this set was used as a discriminator for hierarchical clustering analysis, it identified four distinct subgroups of MS patients and five gene clusters differentially expressed among the subgroups. One of these gene clusters was overexpressed in MS versus CN, and particularly enhanced in the clinically most active subgroup of MS. After 46 of the MS patients were treated with interferon-beta (IFNbeta-1b) for two years, IFNbeta responders were clustered in two of the four MS subgroups. Furthermore, the IFNbeta responders differed from nonresponders in the kinetics of IFN-responsive genes at 3 and 6 months after starting IFNbeta treatment. These results suggest that T-cell gene expression profiling is valuable to identify distinct subgroups of MS associated with differential disease activity and therapeutic response to IFNbeta.

Microarray analysis identifies an aberrant expression of apoptosis and DNA damage-regulatory genes in multiple sclerosis.

To clarify the molecular mechanisms underlying multiple sclerosis (MS)-promoting autoimmune process, we have investigated a comprehensive gene expression profile of T cell and non-T cell fractions of peripheral blood mononuclear cells (PBMC) isolated from 72 MS patients and 22 age- and sex-matched healthy control (CN) subjects by using a cDNA microarray. Among 1258 genes examined, 173 genes in T cells and 50 genes in non-T cells were expressed differentially between MS and CN groups. Downregulated genes greatly outnumbered upregulated genes in MS. More than 80% of the top 30 most significant genes were categorized into apoptosis signaling-related genes of both proapoptotic and antiapoptotic classes. They included upregulation in MS of orphan nuclear receptor Nurr1 (NR4A2), receptor-interacting serine/threonine kinase 2 (RIPK2), and silencer of death domains (SODD), and downregulation in MS of TNF-related apoptosis-inducing ligand (TRAIL), B-cell CLL/lymphoma 2 (BCL2), and death-associated protein 6 (DAXX). Furthermore, a set of the genes involved in DNA repair, replication, and chromatin remodeling was downregulated in MS. These results suggest that MS lymphocytes show a complex pattern of gene regulation that represents a counterbalance between promoting and preventing apoptosis and DNA damage of lymphocytes.

Microarray analysis identifies interferon beta-regulated genes in multiple sclerosis.

The molecular mechanisms for the interferon beta (IFNbeta) treatment of multiple sclerosis (MS) remain to be characterized. Using cDNA microarray technology, we have compared the gene expression profile of T and non-T cells derived from relapsing-remitting MS before and after treatment with IFNbeta-1b. IFNbeta treatment significantly altered expression of 21 genes out of 1263 at 3 and 6 months after treatment. These genes included nine with IFN-responsive promoter elements. Whereas there was no change in Th1 or Th2 marker genes, some of the changes were unexpected but coincided with the beneficial effect of IFNbeta in MS.