CO2 modulates the inflammatory cytokine release of primary human pleural macrophages

It is well known that CO (2) used during laparoscopy affects the peritoneal surface and local inflammatory response, including the inflammatory reactivity of peritoneal macrophages. However, little is known about the local effects of CO (2) during thoracoscopy. In a previous study we have shown that in healthy adolescents, macrophages are the dominant cell population on the pleural surface. Therefore, we examined the effects of CO (2) on the inflammatory response of primary human pleural macrophages.

Human primary macrophages were harvested lavage from healthy adolescents undergoing elective surgery for pectus bar correction (n=8). After purification and 24 h resting, cells were incubated for 2 h in 100% CO (2), 5% CO (2) or 95% inert helium with 5% CO (2) as hypoxic control. After incubation cells were stimulated with LPS for 4 h and 24 h. The release of TNF-alpha, IL-8, IL-6, IL-10 and IL-1 beta were determined by ELISA.

CO (2), but not hypoxia, induced a significant reduction in the release of TNF-alpha and IL-8 as well as a significant increase in the release of IL-10 and IL-1 beta within the first 4 h after incubation. The levels of IL-6 and the release of cytokines at 24 h after incubation were not significantly affected.

CO (2) directly modulates the immediate inflammatory response of pleural macrophages. Therefore, CO (2) insufflation during thoracoscopy could lower the local stress response, but does not appear to have a lasting effect.