Previous studies reported associations of IFITM3 SNP rs12252 with severe influenza, but evidence of association and the mechanism of risk remains controversial. We prioritized SNPs in IFITM3 based on putative biological function and identified rs34481144 in the 5′ UTR. We found evidence of a novel association of rs34481144 with severe influenza in three influenza-infected cohorts characterized by different levels of influenza illness severity. We determined the role of rs34481144 as an expression quantitative trait loci (eQTL) for IFITM3, with the risk allele associated with lower mRNA expression. The risk allele was found to have decreased IRF3 binding and increased CTCF binding in promoter-binding assays, and risk allele carriage diminished transcriptional correlations among neighboring genes, indicative of CTCF boundary activity. Furthermore, the risk allele disrupts a CpG site that undergoes differential methylation in CD8 T-cell subsets. Carriers of the risk allele had reduced CD8 T-cells in their airways during natural influenza infection, consistent with IFITM3 promoting airway CD8 T-cell accumulation, indicating that a critical function for IFITM3 may be to promote immune cell persistence at mucosal sites. Our study identifies a new regulator of IFITM3 expression that associates with CD8 T-cell levels in the airways and a spectrum of clinical outcomes.
Highlights d A searchable database of eQTL from macula and peripheral retina and RPE/choroid d Single-cell expression from human retina and RPE with cell subtype resolution d Integrative analysis of bulk and single-cell transcriptomics in the human eye d Co-localization of GWAS and eQTL identified putative causal genes for AMD
Genentech, National Institutes of Health, Francis Family Foundation, Pulmonary Fibrosis Foundation, Nina Ireland Program for Lung Health, US Department of Veterans Affairs.
Geographic atrophy is an advanced form of age-related macular degeneration (AMD) and a leading cause of vision loss for which there are no approved treatments. Genetic studies in AMD patients have implicated dysregulation of the alternative complement pathway in the pathogenesis of geographic atrophy. Lampalizumab is a potential therapeutic that targets complement factor D, a pivotal activator of the alternative complement pathway. The MAHALO phase 2 clinical trial was a multicenter, randomized, controlled study that evaluated lampalizumab administered by intravitreal injection monthly ( = 42) and every other month ( = 41) versus sham control ( = 40) in patients with geographic atrophy secondary to AMD. The primary endpoint was the mean change in lesion area from baseline to month 18 as measured by fundus autofluorescence. Specific AMD-associated genetic polymorphisms were also analyzed. The MAHALO study met its primary efficacy endpoint with an acceptable safety profile; monthly lampalizumab treatment demonstrated a 20% reduction in lesion area progression versus sham control [80% confidence interval (CI), 4 to 37%]. A more substantial monthly treatment benefit of 44% reduction in geographic atrophy area progression versus sham control (95% CI, 15 to 73%) was observed in a subgroup of complement factor I () risk-allele carriers (57% of the patients analyzed were risk-allele carriers). The MAHALO study shows a potential treatment effect in patients with geographic atrophy and supports therapeutic targeting of the alternative complement pathway for treating AMD pathogenesis.
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