Risk HLA Variants Affect the T-Cell Repertoire in Multiple Sclerosis.

BACKGROUND AND OBJECTIVES: The major histocompatibility complex (MHC) locus has a predominant role in the genetic predisposition to multiple sclerosis (MS), with 32 associations found to be involved. We aimed to investigate the impact of MHC MS-risk alleles on T-cell repertoire in patients with MS. METHODS: We studied 161 untreated patients with relapsing-remitting MS for whom Class I and II human leukocyte antigen (HLA) alleles were inferred from whole-genome genotyping data, and T-cell receptor (TCR) CDR3 sequences were obtained through next-generation sequencing. T-cell repertoire features including diversity, public clones, and architecture were evaluated. RESULTS: We identified 5 MS-risk loci associated with TCR diversity: HLA-DRB1*15:01 (7.65 × 10-3), rs9271366 (1.96 × 10-3), rs766848979 A (1.89 × 10-2), rs9277626 (2.95 × 10-2), and rs11751659 (1.92 × 10-2), with evidence of expanded clonotypes in carriers of risk alleles. Moreover, HLA-DRB1*15:01 (4.99 × 10-3), rs9271366 (6.54 × 10-3), rs1049079 C (4.37 × 10-2), AA DQΒ1 position -5 L (1.05 × 10-3), and AA DQΒ1 position 221 Q (9.39 × 10-4) showed an association with the CDR3 aminoacidic sequence architecture, suggesting an impact on the antigen recognition breadth as well. Evaluating the sharing of clones across MS-risk allele carrier individuals revealed the presence of highly shared clonotypes predicted to target viral antigens, including Epstein-Barr virus. DISCUSSION: Our study supports the association between MHC-risk alleles and macrofeatures of the T-cell repertoire in the context of MS. Further studies are needed to understand the underlying molecular mechanisms.

Long-Term Clinical Outcomes of Hematopoietic Stem Cell Transplantation in Multiple Sclerosis.

OBJECTIVE: To determine whether autologous hematopoietic stem cell transplantation (aHSCT) is able to induce durable disease remission in people with multiple sclerosis (MS), we analyzed the long-term outcomes after transplant in a large cohort of MS patients. METHODS: To be included, a minimum data set (consisting of age, MS phenotype, EDSS at baseline, information on transplant technology and at least 1 follow-up visit after transplant) was required. RESULTS: 210 patients were included [relapsing-remitting (RR)MS=122(58%)]. Median baseline EDSS was 6(1-9), mean follow-up was 6.2(±5.0) years. Among RRMS patients, disability worsening-free survival (95%CI) was 85.5%(76.9-94.1%) at 5 years and 71.3%(57.8-84.8%) at 10 years. In patients with progressive MS, disability worsening-free survival was 71.0%(59.4-82.6%) and 57.2%(41.8-72.7%) at 5 and 10 years, respectively. In RRMS patients, EDSS significantly reduced after aHSCT [p=0.001; mean EDSS change per year -0.09 (95%CI=-0.15 to -0.04%)]. In RRMS patients, the use of the BEAM+ATG conditioning protocol was independently associated with a reduced risk of NEDA-3 failure [HR=0.27(0.14-0.50), p<0.001]. Three patients died within 100-days from aHSCT (1.4%); no deaths occurred in patients transplanted after 2007. CONCLUSIONS: aHSCT prevents disability worsening in the majority of patients and induces durable improvement in disability in patients with RRMS. The BEAM+ATG conditioning protocol is associated with a more pronounced suppression of clinical relapses and MRI inflammatory activity. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for people with MS, aHSCT induces durable disease remission in most patients.