Treatment with 7% and 10% CO 2 enhanced expression of IL-1β, TNF-α, and IL-6 in hypoxic cultures of human whole blood.

Objective This study investigated whether hypercapnia influenced the inflammatory response of hypoxic blood. Methods Human whole blood was cultured with 0.2% oxygen (O-2) and treated with 5%, 7%, or 10% carbon dioxide (CO2). Interleukin (IL)-1 beta, tumor necrosis factor (TNF)-alpha, and IL-6 were evaluated in whole blood cultures. Reactive oxygen species (ROS) production and expression levels of caspase-1 and IL-1 beta were evaluated in THP-1 monocytic cells. Results IL-1 beta, TNF-alpha, and IL-6 levels were higher in the hypoxia + 7% CO2 group than in the hypoxia + 5% CO2 group. The hypoxia + 10% CO2 group had the highest IL-1 beta, TNF-alpha, and IL-6 levels, compared with the hypoxia + 7% CO2 and hypoxia + 5% CO2 groups. Expression levels of IL-1 beta, TNF-alpha, and IL-6 were significantly negatively correlated with pH levels in the cell culture medium. Treatment with 7% and 10% CO2 increased the production of ROS and the expression of caspase-1 and IL-1 beta in hypoxia-activated THP-1 cells. Conclusions High levels of CO2 treatment increased expression levels of IL-1 beta, TNF-alpha, and IL-6 in hypoxic whole blood cultures. High levels of CO2-induced ROS overproduction and NLRP3 inflammasome activation in monocytes may comprise a target to mitigate the inflammatory response of hypoxic blood.