Faculty Bibliography

BACKGROUND:While common variant non-HLA (human leukocyte antigen) alleles have been associated with MS risk, their role in disease course is less clear. We sought to determine whether established multiple sclerosis (MS) genetic susceptibility factors are associated with relapse rate in children and an independent cohort of adults with MS. METHODS:Genotyping was performed for 182 children with MS or clinically isolated syndrome with high risk for MS from two Pediatric MS Centers. They were prospectively followed for relapses. Fifty-two non-HLA MS susceptibility single nucleotide polymorphisms (SNPs) were evaluated for association with relapse rate. Cox regression models were adjusted for sex, genetic ancestry, disease-modifying therapy (DMT), 25-OH vitamin D level and HLA-DRB1*15:01/03 status. Investigation of pediatric subject SNP results was performed using a second cohort of 141 adult MS subjects of Northern European ancestry from the Southern Tasmanian Multiple Sclerosis Longitudinal Study. RESULTS:For pediatric subjects, 408 relapses were captured over 622 patient-years of follow-up. Four non-HLA risk SNPs (rs11154801, rs650258, rs12212193, rs2303759) were associated with relapses (p < 0.01) in the pediatric subjects. After adjustment for genetic ancestry, sex, age, vitamin D level, DMT use and HLA-DRB1*15 status, having two copies of the MS risk allele within AHI1 (rs11154801) was associated with increased relapses among children (HR = 1.75,95%CI = 1.18-2.48, p = 0.006) and this result was also observed among adults (HR = 1.81,95%CI = 1.05-3.03, p = 0.026). CONCLUSIONS:Our results suggest that the MS genetic risk variant within the gene AHI1 may contribute to disease course in addition to disease susceptibility.

BACKGROUND: Multiple sclerosis (MS) is a presumed autoimmune disease caused by genetic and environmental factors. It is hypothesized that environmental exposures (such as air and water quality) trigger the innate immune response thereby activating a pro-inflammatory cascade. OBJECTIVE: To examine potential environmental factors in pediatric MS using geographic information systems (GIS). METHODS: Pediatric MS cases and healthy controls were identified as part of an ongoing multicenter case-control study. Subjects' geographic locations were mapped by county centroid to compare to an Environmental Quality Index (EQI). The EQI examines 5 individual environmental components (air, land, water, social, built factors). A composite EQI score and individual scores were compared between cases and controls, stratified by median proximity to enrollment centers (residence <20 or >/=20 miles from the recruiting center), using logistic regression. RESULTS: Of the 287 MS cases and 445 controls, 46% and 49% respectively live in areas where the total EQI is the highest (worst environmental quality). Total EQI was not significantly associated with the odds for MS (p = 0.90 < 20 miles from center; p = 0.43 >/= 20 miles); however, worsening air quality significantly impacted the odds for MS in those living near a referral center (OR = 2.83; 95%CI 1.5, 5.4) and those who reside >/= 20 miles from a referral center (OR = 1.61; 95%CI 1.2, 2.3). CONCLUSION: Among environmental factors, air quality may contribute to the odds of developing MS in a pediatric population. Future studies will examine specific air constituents and other location-based air exposures and explore potential mechanisms for immune activation by these exposures.

Objective: To confirm our preliminary findings of association between EBV, CMV and HSV-1 remote infections, serum 25(OH)vitamin D levels and pediatric-MS in a large national case-control study. Background: Prior studies have suggested possible associations between viral infections acquired during childhood and development of MS. Moreover, vitamin D deficiency and genetic polymorphisms in the vitamin D pathway may alter the immune response and are associated with increased risk of pediatric and adult MS. Design/Methods: Patients with pediatric-onset MS or CIS and frequency-matched controls were recruited at 16 pediatric MS centers across the US. Batched Epstein-Barr virus(EBV)-viral capsid antigen(VCA), Epstein-Barr nuclear antigen-1(EBNA-1), EBV-early antigen(EA), CMV, HSV-1 and -2 serostatus were tested by ELISA.25(OH)vitamin D levels were determined by chemoluminescence. The rates of viral seropositivity and serum levels of vitamin D were compared between cases and controls in analyses adjusted for possible confounders such as age, sex, race and ethnicity. DRB1*1501 status was determined using SNP typing. Results: Serum samples from 360 pediatric cases(mean age: 15.2+/-3.2 years, 64% females, mean disease duration 354+/-321 days)and 496 healthy controls(mean age:14.3+/-3.8 years, 52% females)were tested for EBV, CMV and HSV antibodies and 25(OH)vitamin D. In a model adjusting for age, sex, race and ethnicity, a remote infection with EBV(anti-EBNA1 IgG positive)was strongly associated with higher risk of developing pediatric-onset MS(OR:3.6, 95%CI 2.1-6.3). HSV-1 seropositivity was also associated with pediatric-onset MS(OR:1.4, 95%CI 1.001-2.011). There was no association between serostatus for CMV and HSV-2 and risk of pediatric MS. For vitamin D analyses, we compared controls with 42 cases who were recruited within 45 days of disease onset as serum levels could not yet be substantially altered by vitamin D supplementation. There was a trend towards an association between lower serum levels of vitamin D and the risk of developing pediatric MS. For each 1 ng increase in 25(OH)vitamin D serum levels, there was a 3% reduction in the risk of pediatric MS onset(OR:0.77, 95%CI 0.93-1.01). Analyses stratifying by DRB1*1501 status are ongoing. Conclusions: Our preliminary results support an association between prior EBV and HSV-1 infection, and vitamin D deficiency and development of pediatric-onset MS

BACKGROUND: Salt intake was reported to be associated with increased clinical and MRI activity in adult patients with relapsing-remitting multiple sclerosis (MS). OBJECTIVE: To determine if salt intake is associated with time to relapse in patients with paediatric-onset MS. METHODS: Paediatric-onset MS and patients with clinically isolated syndrome (CIS) within 4 years of disease onset were recruited from 15 paediatric MS centres in the USA as part of a case-control study. Patients with available prospective relapse data subsequent to enrolment were included in this project. Dietary sodium intake was assessed by self-report questionnaire using the validated Block Kids Food Screener. Cox proportional-hazards regression models were employed to determine the association of sodium density, excess sodium intake and sodium density tertiles with time to relapse following study enrolment, adjusting for several confounders. RESULTS: 174 relapsing-remitting MS/CIS patients were included in this analysis (mean age of 15.0 years, and 64.9% females). Median duration of follow-up was 1.8 years. In an unadjusted analysis, density of daily sodium intake was not associated with time to relapse, and patients with excess sodium intake had no decrease in time to relapse as compared with patients with non-excess sodium intake. The multivariable analysis demonstrated that patients in the medium and high tertile of sodium density had a HR of 0.69 (95% CI 0.37 to 1.30, p=0.25) and 1.37 (95% CI 0.74 to 2.51, p=0.32) compared with patients in the lowest tertile, respectively. CONCLUSIONS: Higher salt intake was not associated with decreased time to relapse in patients with paediatric-onset MS.

BACKGROUND: Genetic ancestry, sex, and individual alleles have been associated with multiple sclerosis (MS) susceptibility. OBJECTIVE: To determine whether established risk factors for disease onset are associated with relapse rate in pediatric MS. METHODS: Whole-genome genotyping was performed for 181 MS or high-risk clinically isolated syndrome patients from two pediatric MS centers. Relapses and disease-modifying therapies were recorded as part of continued follow-up. Participants were characterized for 25-hydroxyvitamin D serum status. Ancestral estimates (STRUCTURE v2.3.1), human leukocyte antigen (HLA)-DRB1*15 carrier status (direct sequencing), sex, and a genetic risk score (GRS) of 110 non-HLA susceptibility single-nucleotide polymorphisms (SNPs) were evaluated for association with relapse rate with Cox and negative binomial regression models. RESULTS: Over 622 patient-years, 408 relapses were captured. Girls had greater relapse rate than boys (incident rate ratio (IRR) = 1.40, 95% confidence interval (CI) = 1.04-1.87, p = 0.026). Participants were genetically diverse; ~40% (N = 75) had <50% European ancestry. HLA-DRB1*15 status modified the association of vitamin D status (pixn = 0.022) with relapse rate (per 10 ng/mL, in DRB1*15+ hazard ratio (HR) = 0.72, 95% CI = 0.58-0.88, p = 0.002; in DRB1*15- HR = 0.96, 95% CI = 0.83-1.12, p = 0.64). Neither European ancestry nor GRS was associated with relapse rate. CONCLUSION: We demonstrate that HLA-DRB1*15 modifies the association of vitamin D status with relapse rate. Our findings emphasize the need to pursue disease-modifying effects of MS genes in the context of environmental factors.