Elevated clonal hematopoiesis in 9/11 first responders has distinct age-related patterns and relies on IL1RAP for clonal expansion

Environmental exposures are linked to precancerous hematologic conditions, but studies in cohorts with well-defined exposures are limited. We sequenced blood samples from a large cohort of first-responders exposed to the aerosolized dust and carcinogens from the 9/11 World Trade Center (WTC) disaster and observed a significantly higher prevalence of clonal hematopoiesis (CH) mutations when compared to two sets of control cohorts after controlling for age, race, and sex. Younger exposed first-responders exhibited unconventional CH mutations, with defective DNA repair signatures. Leukemia risk was elevated (3.7% vs. 0.6%, OR=5.73) in WTC-exposed responders with CH versus without CH. Exposure to particulate matter collected from WTC site impaired healthy stem cell while expanding Tet2-mutant CH clones in mice. Inflammation sensor, IL1RAP, was overexpressed in murine CH, and genetic knockdown inhibited mutant clone growth in-vivo. This study links discrete environmental exposure to hematopoietic mutations and leukemia, identifying IL1RAP as a novel therapeutic target in CH.