Genetic Contributors to the Impact of Sex on Heterogeneity in Flu Infection

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The 1918 influenza pandemic is estimated to have killed 1 in 20 people worldwide. Influenza A virus (IAV) infections usually do not cause such severe disease for the ~30 million infected every year in the United States alone (2014-2015). However, there are broad differences in IAV susceptibility and severity, with outcomes from asymptomatic infections (~16%) to death (0.2% in 2014-2015). These differences arise from the complex interplay of exposure, environment, IAV genetics, and host factors. A crucial host factor that contributes to heterogeneity of IAV infection is biological sex. For children and older individuals, males are more likely to experience severe disease, while females of child-bearing age have greater severity. We hypothesize that sex differences in gene expression are a major driver of heterogeneity in IAV infection. In the parent award, we are identifying sex-specific differences in gene expression that regulate IAV burden and host response in human cells, IAV challenge volunteers, and natural populations. In this Supplement, we propose to use two Common Fund resources to expand the biological understanding of sex differences during IAV infection that will be revealed from this study and to determine the generalizability of our findings across all human tissues. In the first supplement Aim, we will use LINCS to understand sex differences in the response to IAV infection in cells and human volunteers. The LINCS signatures database, as implemented in the iLINCS portal, will be leveraged to identify the critical genes that drive male- or female-biased gene expression following IAV infection. Specifically, querying the LINCS CGS (consensus gene knockdown signatures) and LINCS gene overexpression signatures will reveal genes that when knocked down or overexpressed mimic signatures observed in male and female lymphoblastoid cell lines (LCLs) and volunteers following IAV infection. Such signatures may reveal signaling pathways that could explain some of the sex differences seen during IAV infection in cells and humans. Further, LINCS analysis using chemical perturbagen signatures will reveal small molecule reversers and mimickers of the gene expression changes that will serve as starting points for pharmacological targeting to improve outcomes in severe flu infection. In the second supplement Aim, we will use GTEx to determine the generalizability of sex-biased genes and expression quantitative trait loci (sb- Genes and sb-eQTLs) during IAV infection across human tissues. In the parent grant, we are identifying sb- Genes and sb-eQTLs in IAV-infected LCLs and in whole blood and nasal curettage from human challenge volunteers. We will use GTEx to determine whether sb-Genes and sb-eQTLs identified in IAV-infected LCLs and whole blood from human volunteers are applicable to other tissues, increasing the generalizability of our findings. This Supplement Application proposes to utilize two Common Fund Resources, LINCS and GTEx, to increase the insight and generalizability of the parent award. Doing so will increase our understanding of the genetic basis for sex differences and could lead to novel therapeutic strategies.