Genetic and molecular assessment of the relationship between smoking and EBV reactivation: A two-sample Mendelian randomization and in-vitro experimental study

ObjectiveTo assess whether modifiable lifestyle factors (particularly tobacco smoking) have a potential causal effect on Epstein-Barr virus (EBV) reactivation proxied by anti-EBV IgG seropositivity using Mendelian randomization (MR), and to explore the underlying mechanism <i>in vitro</i>.MethodsWe performed a two-sample Mendelian randomization (MR) study (retrospective secondary analysis) using de-identified genome-wide association study (GWAS) summary statistics for 83 dietary habits, 5 tobacco smoking behaviors, and 4 sleep traits with anti-EBV IgG seropositivity as the outcome. We further conducted experiments in EBV-positive B-cell lines to examine mechanisms.ResultsGenetically proxied smoking initiation and lifetime smoking were associated with higher odds of anti-EBV IgG seropositivity, whereas an older age at smoking initiation was associated with lower odds. No consistent associations were observed for sleep traits; dietary findings were heterogeneous across discovery and replication cohorts. <i>In vitro</i>, nicotine increased EBV-DNA levels and up-regulated lytic genes (BZLF1, BRLF1) and gp350, with concordant increases in BZLF1 and EA-D proteins; these effects coincided with ROS accumulation and were attenuated by the ROS scavenger NAC.ConclusionsOur findings support that smoking is associated with EBV seropositivity and nicotine-induced oxidative stress as a plausible mechanism. Modifying smoking behaviors (e.g. delaying initiation and reducing lifetime exposure) may help lower anti-EBV IgG seropositivity.