Despite the fact that CD4+CD25+Foxp3+ regulatory T cells (Treg cells) play a central role in maintaining self-tolerance and that IL-17-producing CD4+ T cells (Th17 cells) are pathogenic in many autoimmune diseases, evidence to date has indicated that Th17 cells are resistant to suppression by human Foxp3+ Treg cells. It was recently demonstrated that CD39, an ectonucleotidase which hydrolyzes ATP, is expressed on a subset of human natural Treg cells. We found that although both CD4+CD25highCD39+ and CD4+CD25highCD39− T cells suppressed proliferation and IFN-γ production by responder T cells, only the CD4+CD25highCD39+, which were predominantly FoxP3+, suppressed IL-17 production, whereas CD4+CD25highCD39− T cells produced IL-17. An examination of T cells from multiple sclerosis patients revealed a normal frequency of CD4+CD25+CD127lowFoxP3+, but interestingly a deficit in the relative frequency and the suppressive function of CD4+CD25+CD127lowFoxP3+CD39+ Treg cells. The mechanism of suppression by CD39+ Treg cells appears to require cell contact and can be duplicated by adenosine, which is produced from ATP by the ectonucleotidases CD39 and CD73. Our findings suggest that CD4+CD25+Foxp3+CD39+ Treg cells play an important role in constraining pathogenic Th17 cells and their reduction in multiple sclerosis patients might lead to an inability to control IL-17 mediated autoimmune inflammation.

No abstract

Frontotemporal dementia (FTD) is the second most common cause of dementia following Alzheimer's disease (AD). Between 20 and 50% of cases are familial. Mutations in MAPT, GRN and C9orf72 are found in 60% of familial FTD cases. C9orf72 mutations are the most common and account for 25%. Rarer mutations (<5%) occur in other genes such as VPC, CHMP2B, TARDP, FUS, ITM2B, TBK1 and TBP. The diagnosis is often challenging due to symptom overlap with AD and other conditions. We review the genetics, clinical presentations, neuroimaging, neuropathology, animal studies and therapeutic trials in FTD. We describe clinical scenarios including the original family with the tau stem loop mutation (+14) and also the recently discovered 'missing tau' mutation +15 that 'closed the loop' in 2015.

The present study indicated that both early sensory and later cognitive ERP components are impaired in MS patients relative to controls.

BackgroundThe relationship between prevalence of multiple sclerosis (MS) and latitude may be due to both genetic and environmental factors. The hypothesis that, in Ireland, MS prevalence is increasing and that northesouth differences relate to variation in serum 25-hydroxyvitamin D (25(OH)D) levels was tested in this study.

No abstract

Frontotemporal lobar degeneration comprises a group of disorders characterized by behavioural, executive, language impairment and sometimes features of parkinsonism and motor neuron disease. In 1994 we described an Irish-American family with frontotemporal dementia linked to chromosome 17 associated with extensive tau pathology. We named this disinhibition-dementia-parkinsonism-amyotrophy complex. We subsequently identified mutations in the MAPT gene. Eleven MAPT gene splice site stem loop mutations were identified over time except for 5' splice site of exon 10. We recently identified another Irish family with autosomal dominant early amnesia and behavioural change or parkinsonism associated with the 'missing' +15 mutation at the intronic boundary of exon 10. We performed a clinical, neuropsychological and neuroimaging study on the proband and four siblings, including two affected siblings. We sequenced MAPT and performed segregation analysis. We looked for a biological effect of the tau variant by performing real-time polymerase chain reaction analysis of RNA extracted from human embryonic kidney cells transfected with exon trapping constructs. We found a c.915+15A>C exon 10/intron 10 stem loop mutation in all affected subjects but not in the unaffected. The c.915+15A>C variant caused a shift in tau splicing pattern to a predominantly exon 10+ pattern presumably resulting in predominant 4 repeat tau and little 3 repeat tau. This strongly suggests that the c.915+15A>C variant is a mutation and that it causes frontotemporal dementia linked to chromosome 17 in this pedigree by shifting tau transcription and translation to +4 repeat tau. Tau (MAPT) screening should be considered in families where amnesia or atypical parkinsonism coexists with behavioural disturbance early in the disease process. We describe the final missing stem loop tau mutation predicted 15 years ago. Mutations have now been identified at all predicted sites within the 'stem' when the stem-loop model was first proposed and no mutations have been found within the 'loop' region as expected. Therefore we 'close the tau loop' having 'opened the loop' 21 years ago.

A functional OAS1 SNP, AA genotype, confers susceptibility to MS and the GG genotype may protect against increased disease activity.