JC Polyomavirus Infection Is Strongly Controlled by Human Leucocyte Antigen Class II Variants

JC polyomavirus (JCV) carriers with a compromised immune system, such as in HIV, or subjects on immune-modulating therapies, such as anti VLA-4 therapy may develop progressive multifocal leukoencephalopathy (PML) which is a lytic infection of oligodendrocytes in the brain. Serum antibodies to JCV mark infection occur only in 50-60% of infected individuals, and high JCV-antibody titers seem to increase the risk of developing PML. We here investigated the role of human leukocyte antigen (HLA), instrumental in immune defense in JCV antibody response. Anti-JCV antibody status, as a surrogate for JCV infection, were compared to HLA class I and II alleles in 1621 Scandinavian persons with MS and 1064 population-based Swedish controls and associations were replicated in 718 German persons with MS. HLA-alleles were determined by SNP imputation, sequence specific (SSP) kits and a reverse PCR sequence-specific oligonucleotide (PCR-SSO) method. An initial GWAS screen displayed a strong HLA class II region signal. The HLA-DRB1*15 haplotype was strongly negatively associated to JCV sero-status in Scandinavian MS cases (OR\u200a=\u200a0.42, p\u200a=\u200a7 710(-15)) and controls (OR\u200a=\u200a0.53, p\u200a=\u200a2 710(-5)). In contrast, the DQB1*06:03 haplotype was positively associated with JCV sero-status, in Scandinavian MS cases (OR\u200a=\u200a1.63, p\u200a=\u200a0.006), and controls (OR\u200a=\u200a2.69, p\u200a=\u200a1 710(-5)). The German dataset confirmed these findings (OR\u200a=\u200a0.54, p\u200a=\u200a1 710(-4) and OR\u200a=\u200a1.58, p\u200a=\u200a0.03 respectively for these haplotypes). HLA class II restricted immune responses, and hence CD4+ T cell immunity is pivotal for JCV infection control. Alleles within the HLA-DR1*15 haplotype are associated with a protective effect on JCV infection. Alleles within the DQB1*06:03 haplotype show an opposite association. These associations between JC virus antibody response and human leucocyte antigens supports the notion that CD4+ T cells are crucial in the immune defence to JCV and lays the ground for risk stratification for PML and development of therapy and prevention

Association of Genetic Markers with CSF Oligoclonal Bands in Multiple Sclerosis Patients

OBJECTIVE: to explore the association between genetic markers and Oligoclonal Bands (OCB) in the Cerebro Spinal Fluid (CSF) of Italian Multiple Sclerosis patients. METHODS: We genotyped 1115 Italian patients for HLA-DRB1*15 and HLA-A*02. In a subset of 925 patients we tested association with 52 non-HLA SNPs associated with MS susceptibility and we calculated a weighted Genetic Risk Score. Finally, we performed a Genome Wide Association Study (GWAS) with OCB status on a subset of 562 patients. The best associated SNPs of the Italian GWAS were replicated in silico in Scandinavian and Belgian populations, and meta-analyzed. RESULTS: HLA-DRB1*15 is associated with OCB+: p\u200a=\u200a0.03, Odds Ratio (OR)\u200a=\u200a1.6, 95% Confidence Limits (CL)\u200a=\u200a1.1-2.4. None of the 52 non-HLA MS susceptibility loci was associated with OCB, except one SNP (rs2546890) near IL12B gene (OR: 1.45; 1.09-1.92). The weighted Genetic Risk Score mean was significantly (p\u200a=\u200a0.0008) higher in OCB+ (7.668) than in OCB- (7.412) patients. After meta-analysis on the three datasets (Italian, Scandinavian and Belgian) for the best associated signals resulted from the Italian GWAS, the strongest signal was a SNP (rs9320598) on chromosome 6q (p\u200a=\u200a9.4 710(-7)) outside the HLA region (65 Mb). DISCUSSION: genetic factors predispose to the development of OCB

Association between DPP6 polymorphism and the risk of progressive multiple sclerosis in Northern and Southern Europeans

Background: In this study, we investigated the role of the dipeptidyl-peptidase-6 (DPP6) gene in the etiopathogenesis of progressive forms of multiple sclerosis (PrMS).This gene emerged as a candidate gene in a genome-wide association study (GWAS) performed in an Italian sample of PrMS and controls in which two SNPs located in the gene (rs6956703 and rs11767658) showed evidence of association (nominal p-value<10-4) (Martinelli-Boneschi et al.) [18]. Moreover, the gene is highly expressed in the central nervous system, and it has been found to be associated with sporadic cases of amyotrophic lateral sclerosis which shares some feature with PrMS. Methods: We genotyped 19 SNPs selected using a direct and tagging approach in 244 Italian PrMS and 225 controls, and we measured the expression levels of the gene in 13 PrMS cases and 25 controls. Results: Five out of 19 SNPs were found to be associated with the disease (adjusted p<0.05), and they have been tested in an independent sample of 179 primary progressive MS and 198 controls from Northern Europe. None of the SNPs was replicated, but combined analysis confirmed the presence of association for rs2046748 (p=2.5 710-3,OR=1.82, 95%CI=1.24-2.69). Conclusions: These results, inflated by the limited sample size determined by the rarity of this condition, suggest a possible role of this gene in the susceptibility to PrMS, at least in Southern Europeans. Moreover, DPP6 was over-expressed in PrMS patients compared to controls

A genome-wide association study in progressive multiple sclerosis

Background: The role played by genetic factors in influencing the clinical course of multiple sclerosis (MS) is not yet well established.Objective: We aimed to identify genetic variants associated with progressive MS (PrMS).Methods: We conducted a genome-wide association study (GWAS) in 197 patients with PrMS and 234 controls of Italian origin. We tested the top 20 single nucleotide polymorphisms (SNPs) with suggestive evidence of association (p-value<10-4) in two independent sets of primary progressive MS cases and controls.Results: We identified a risk-associated SNP in the HLA region in linkage disequilibrium (LD) with DRB1*1501 and DQB*0602 loci, with genome-wide significance (rs3129934T, pcombined=6.7\uc3\u9710-16, OR=2.34, 95% CI=1.90-2.87), and a novel locus on chromosome 7q35 with suggestive evidence of association (rs996343G, pcombined=2.4\uc3\u9710-5, OR=0.70, 95% CI=0.59-0.83) which maps within a human endogenous retroviral (HERV) element. The new locus did not have a 'cis' effect on RNA expression in lymphoblastic cell lines, but pathway analyses of 'trans' effects point to an expression regulation of genes involved in neurodegeneration, including glutamate metabolism (p<0.01) and axonal guidance signalling (p<0.02).Conclusions: We have confirmed the established association with the HLA region and, despite the low statistical power of the study, we found suggestive evidence for association with a novel locus on chromosome 7, with a putative regulatory role