Impact of Moderate Altitude on Pro-Inflammatory Cytokines in Healthy Volunteers.

Background: The induction of microvascular inflammation and the effects on cytokine production in blood due to hypoxia has been shown in the past. We have previously reported a statistically significant increase of the pro-inflammatory cytokine interleukin-8 (IL-8) in normobaric hypoxia in the setting of a hypoxia-chamber. In the present study, we sought to analyze plasma levels of inflammatory cytokines in a real-life stetting in order to foster our knowledge on hypoxia induced microvascular inflammation at moderate altitude. Methods: Pro-inflammatory cytokines (IL-8, IL-6, TNF-alpha) were measured in an experimental field study, exposing 18 healthy volunteers to moderate hypoxia while staying at a mountain lodge in Diavolezza, Switzerland (2978 meters above sea level). Plasma cytokine levels were measured by ELISA. Results: In contradiction to our results in a normobaric hypoxia-chamber, exposure to moderate hypoxia led to a significant decrease of plasma IL-8 levels in a real-life setting (from 2.902 (1.046 - 4.984) pg/mL to 1.395 (0.698 - 3.712) pg/mL, p = 0.034). Concentrations of IL-6 and TNF-alpha did not show statistically significant changes in comparison to baseline measurements. Conclusions: The results of this study show a decrease of proinflammatory cytokine IL-8 in a real life setting of moderate altitude in healthy individuals. Initiation of angiogenesis or subliminal stimulus for an altitude-induced inflammatory reaction may be explanations for this unexpected finding.