Abstract
BACKGROUND: Shift work is common in healthcare, especially in emergency and intensive care, to maintain the quality of patient care. Night shifts are linked to health risks such as cardiovascular disease, metabolic disorders, and poor mental health. It has been suggested that inflammatory responses due to the disruption of circadian rhythm may contribute to health risks, but the detailed mechanisms remain unclear. This study aimed to analyze changes in gene expression in whole blood of healthcare workers before and after a night shift and investigate the molecular pathogenesis of these changes and their impact on health. METHODS: This was a single-center, prospective, observational study of four medical doctors working night shifts in the emergency department. Blood samples from the subjects were collected before and after the night shift, and RNA sequencing was performed to analyze changes in gene expression in whole blood. The data obtained were analyzed via Ingenuity Pathway Analysis (IPA) core analysis that included canonical pathway analysis, upstream regulator analysis, and functional network analysis. RNA bulk deconvolution was performed to estimate the relative abundance of immune cells. The IPA analysis match feature was also used to assess similarities of gene expression patterns with other diseases. RESULTS: We identified 302 upregulated and 78 downregulated genes (p < 0.05, |log2-fold change|> 0.5) as genes whose expression changed after the night shift. Canonical pathway analysis revealed that Toll-like receptors and other innate immune response pathways were activated. Upstream regulator analysis and functional network analysis also consistently indicated a predicted activation of innate immune and inflammatory responses. RNA bulk deconvolution showed changes in the proportions of several immune cells. IPA analysis match indicated that gene expression patterns after night shifts were highly correlated with several diseases, including major depressive disorder, in terms of immune and inflammatory responses. CONCLUSION: The results revealed that innate immune and inflammatory responses are elicited after night shifts in healthcare workers and that gene expression patterns correlate with several diseases in terms of immune and inflammatory responses. These findings suggest that shift work may affect health risks through innate immune and inflammatory responses.