Pre-diagnostic genotyping identifies T1D subjects with impaired Treg IL-2 signaling and an elevated proportion of FOXP3+IL-17+ cells.

T-regulatory cells (Tregs) are essential for immune tolerance, and animal studies implicate their dysfunction in type 1 diabetes (T1D) pathogenesis. Tregs require interleukin-2 (IL-2) for their suppressive function, and variants in IL-2/IL-2R pathway genes have been associated with T1D. We previously reported that recent-onset T1D subjects have an increased population of FOXP3lo Tregs that secrete the pro-inflammatory cytokine, interleukin-17 (IL-17). We hypothesize that IL-2 signaling defects may drive T1D development by skewing protective Tregs towards an inflammatory Th17 phenotype. Overall, we found that the proportion of FOXP3+IL-17+ cells in T1D subjects pre-diagnosis was unchanged compared with healthy controls. However, stratification by IL2RA single-nucleotide polymorphisms revealed that T1D subjects with the rs3118470 CC risk variant have Tregs with IL-2 signaling defects and an increased proportion of FOXP3+IL-17+ cells before diagnosis. These data suggest a potential mechanism for genetically controlled loss of Treg function via dysfunctional IL-2 signaling in T1D.

HostSeq: a Canadian whole genome sequencing and clinical data resource.

HostSeq was launched in April 2020 as a national initiative to integrate whole genome sequencing data from 10,000 Canadians infected with SARS-CoV-2 with clinical information related to their disease experience. The mandate of HostSeq is to support the Canadian and international research communities in their efforts to understand the risk factors for disease and associated health outcomes and support the development of interventions such as vaccines and therapeutics. HostSeq is a collaboration among 13 independent epidemiological studies of SARS-CoV-2 across five provinces in Canada. Aggregated data collected by HostSeq are made available to the public through two data portals: a phenotype portal showing summaries of major variables and their distributions, and a variant search portal enabling queries in a genomic region. Individual-level data is available to the global research community for health research through a Data Access Agreement and Data Access Compliance Office approval. Here we provide an overview of the collective project design along with summary level information for HostSeq. We highlight several statistical considerations for researchers using the HostSeq platform regarding data aggregation, sampling mechanism, covariate adjustment, and X chromosome analysis. In addition to serving as a rich data source, the diversity of study designs, sample sizes, and research objectives among the participating studies provides unique opportunities for the research community.