Elevated CO 2 and Temperature Alter Grass Pollen's Ability to Modify Transcriptome and Function of the Nasal Epithelium

ABSTRACT Background Climate change increases exposure to pollen, but the effects of climate‐related factors on the potency of pollen to trigger early events in the epithelium are unknown, despite their significant impact on respiratory health. Objective We aimed to investigate whether climate change affects the capacity of grass pollen to mediate cell functions in human nasal epithelium. Methods Toxicological and immunological responses, and the transcriptomes were analyzed after exposing reconstituted human nasal epithelial tissues to pollen collected from grasses (timothy and meadow foxtail) grown under different climate change conditions (increasing temperature and CO 2 levels). Results Pollen of both grass species grown under current climate conditions altered the expression of genes encoding for cytokines and chemokines, and similar patterns were observed at the protein level. Moreover, pollen exposure reduced epithelial barrier integrity and was associated with increased expression of genes related to tight junctions and tissue repair. Climate change‐modified meadow foxtail pollen decreased the expression of genes related to vesicle‐mediated transport and transcriptional and translational processes, whereas pollen of timothy grass inhibited the expression of genes related to cilium assembly and organization. Conclusions Future grass pollen potentially disrupts cilia function and vesicle‐mediated (cytokine) signaling in human nasal epithelium more than pollen representing current climate. That may hinder appropriate immune reaction activation and foreign substance removal from the airways. Disrupted regulation of gene expression in turn potentially results in adverse system‐level outcomes.