We will perform follow-up functional studies to identify the mechanisms directly linking genetic variation to susceptibility and protection. To perform functional follow-up, we will isolate peripheral blood mononuclear cells (PBMCs) from whole blood from both cases and controls for RNAseq. We will identify genes differentially expressed before and after challenge in vitro, identify further genetic variation that underpins these transcription changes, and investigate the role of genotypes and ancestry in response to stimulation.

We have recently obtained funding from InterMountain Precision Genomics to perform RNA-sequencing of NK cells stimulated with attenuated M.tb as NK cells may play an important role in controlling M.tb.  To provide a more comprehensive overview of the immune transcriptional response to M.tb infection not limited to a specific cell type and to validate our GWAS findings, here we will isolate, stimulate with M.tb and perform RNA-sequencing across peripheral blood mononuclear cells (PBMCs).  We will characterize the relationship of ancestry with the immune response, and integrate these findings with our GWAS results to perform reQTL mapping.  Because samples from the same population will be used to generate both our prior NK and proposed PBMC transcriptomes, we will additionally be able to contrast and compare the transcriptional signatures.  

Our team has a long-standing interest in gene expression and its use in refining functional characterization. Along with modeling RNA-seq diversity in global populations, and specific eQTL modeling in the context of asthma, our team has experience in eQTL mapping for TB susceptibility, and in stimulation experiments, conducted in the renowned Stellenbosch Centre for Tuberculosis. In a recent study led by Dr. Hoal, part of an ongoing collaboration with Dr. Erwin Schurr (McGill University), we genotyped the candidate locus ZXDC in the context of primary cells. While we observed robust expression measurements at this gene, association of re-QTLs for this locus appears population specific. The Moller Lab group has also developed a bioinformatics pipeline to integrate information from previous TB susceptibility GWAS with predicted regulatory information.