Genetic background influences developmental airway smooth muscle program and susceptibility to airway hyperresponsiveness in mice.

Airway structural remodeling and hyperresponsiveness (AHR), hallmarks of asthma, are influenced by genetic variations and adverse exposures. While intrauterine perturbations in lung development have been linked to adult pulmonary disease, the developmental origins of these abnormalities remain poorly understood. Here, we provide evidence of genetic background playing a key role in this process. Using A/J and C57BL/6J mice known for their distinct susceptibility to AHR, we show that A/J embryos selectively develop an aberrant airway smooth muscle (SM) program and AHR in adulthood when exposed transiently to a vitamin A/retinoic acid (RA)-disrupted intrauterine environment in vivo by maternal BMS493 administration. Single-nuclei multiomics identified a mesenchymal cell population overactivating TGFβ targets in response to BMS selectively in A/J lungs. These cells, localized to sites of airway SM initiation and pSMAD2-3, exhibited robust BMS-mediated upregulation of SMAD2-3 targets, including regulators of SM program Pdgfra and Tnc. Functional analyses in vivo and cultured lungs showed aberrant SM formation in areas of overactive TGFβ of BMS-exposed lungs. These abnormalities were prevented by inhibiting TGFβ signaling in utero in RA-deficient embryos. These findings underscore how distinct genetic backgrounds respond to intrauterine perturbations that program airway structure and function, with potential lasting consequences in postnatal pulmonary function.