Differential influence of 1,8-Cineol on distinct hypoxia-related immune alterations in human monocytes.

1,8-Cineol is a natural plant-based therapeutic agent and is commonly used to treat a broad range of acute and chronic airway inflammatory diseases. 1,8-Cineol has recently been shown to attenuate the checkpoint molecule PDL-1 in circulating monocytes in patients with chronic Otitis media (OM) and was associated with an improved clinical outcome. Hypoxia-inducible factor (HIF) is thought to play an essential role in the middle ear inflammatory process, mainly due to dysfunctions of the eustachian tube. However, the unambiguous impact of 1,8-Cineol on hypoxia-driven immune alterations of human monocytes and the related inflammatory microenvironment have not been investigated thus far. Therefore, we used the human monocytes to investigate the impact of 1,8-Cineol on the cellular hypoxia response with regards to expression levels of different adhesion molecules, chemokine receptors, and different cell stress-related proteins. Furthermore, the secretion patterns of a variety of chemokines and cytokines were evaluated. The study aimed to better understand the influence of the monoterpene 1,8-Cineol on hypoxia and normoxia-associated monocyte characteristics and related inflammatory processes, all of which are crucial for the development of various human diseases.