We aimed to study (1) to what extent the influence of low sun exposure on multiple sclerosis (MS) risk is mediated by low vitamin D levels; (2) whether low sun exposure or vitamin D deficiency act synergistically with HLA-DRB1*15:01 and absence of HLA-A*02:01.
Among both ever and never smokers, an interaction between organic solvents, carriage of HLA-DRB1*15, and absence of HLA-A*02 was observed with regard to MS risk, similar to the previously reported gene-environment interaction involving the same MS risk HLA genes and smoke exposure.
Other alleles were underrepresented in MS patients, such as the HLA-DRB1*07 (OR 0.39 [95% CI 0.21-0.73]) and HLA-A*02 (OR 0.56 [95% CI 0.34-0.94]), showing a protective role against the disease.
The difference in MS risk between the extremes was considerable; smokers carrying HLA-DRB1*15 and lacking HLA-A*02 had a 13-fold increased risk compared with never smokers without these genetic risk factors (OR 12.7, 95% CI 10.8-14.9).
We find that the previously investigated single-nucleotide polymorphism rs4774 is associated with MS risk in cases carrying the HLA-DRB1*15 allele (P=0.01, odds ratio (OR): 1.21, 95% confidence interval (CI): 1.04-1.40) or the HLA-A*02 allele (P=0.01, OR: 1.33, 95% CI: 1.07-1.64) and that these associations are independent of the adjacent confirmed MS susceptibility gene CLEC16A.
The recently described interaction between smoking, human leukocyte antigen (HLA) DRB1*15 and absence of HLA-A*02 with regard to multiple sclerosis (MS) risk shows that the risk conveyed by smoking differs depending on genetic background.
We genotyped the human leukocyte antigens HLA-DRB1 and HLA-A, plus a panel of single nucleotide polymorphisms (SNPs) that have been associated with susceptibility to MS and then correlated the genotypes with the levels of CXCL13, as measured with ELISA in the CSF of a total of 663 patients with MS, CIS, other neurological diseases (OND) or OND with an inflammatory component (iOND).
Epstein-Barr virus (EBV) infection, history of infectious mononucleosis (IM) and HLA-A and DRB1 have all been proposed as risk factors for multiple sclerosis (MS).
The association of HLA A*02 with multiple sclerosis (MS) was recently confirmed by the authors, and it was observed that the combined presence of HLA Cw*05 significantly enhanced (threefold) the protective effect of HLA A*02.
The association of multiple sclerosis with the HLA-A single nucleotide polymorphism was tested using logistic regression adjusted for age, sex and HLA-DRB1*1501.
To evaluate the involvement of KIRs and their HLA ligands in the development of MS we performed genotyping of HLA -A, -B, -Cw, -DRB1 and KIRs loci in 121 RRMS patients and 103 healthy controls (HC).
HLA-A*02 conferred a statistically robust MS protection (odds ratio, OR=0.61; 95% confidence intervals, CI=0.51-0.72, P<10(-9)), which was independent of DRB1*15 and of any other DRB1* allele and remained similar after accounting for the other two analyzed class I markers.
We have generated humanized mice expressing the multiple sclerosis-associated MHC class I alleles HLA-A(*)0301 (encoding human leukocyte antigen-A3 (HLA-A3)) and HLA-A(*)0201 (encoding HLA-A2) and a myelin-specific autoreactive T cell receptor (TCR) derived from a CD8(+) T cell clone from an individual with multiple sclerosis to study mechanisms of disease susceptibility.
We identified significant effects on MS susceptibility of HLA-A*2 (OR: 0.51; P = 0.05) and A*3 (OR: 2.85; P = 0.005), and two coding polymorphisms in the MOG gene (V145I: P = 0.01, OR: 2.2; V142L: P = 0.04, OR: 0.45) after full conditioning on HLA-DRB1.
Therefore, this detailed in vivo characterization provides a hierarchy of candidate epitopes for MOG-specific CD8(+) T cell responses in HLA-A*0201 MS patients identifying the encephalitogenic MOG(181) epitope as a primary candidate.
This study analysed the effect of HLA-A on clinical variables in a large Scandinavian sample set, but could not identify any significant contribution from HLA-A on the clinical phenotype in MS.
Using transmission disequilibrium test and haplotype analyses, we found positive associations between MS and several HLA-DRB1*15-HLA-A haplotypes including HLA-DRB1*15-HLA-A*02 (P = 2.41 x 10(-5)) and -HLA-A*03 (P = 8.42 x 10(-6)) and several HLA-DRB1*15-HLA-B haplotypes including HLA-DRB1*15-HLA-B*07 (P = 2.23 x 10(-10)).