Differential gene transcription following intravenous injection of air bubbles in rats with varying resistance to decompression sickness.

Abstract

Decompression sickness (DCS) is a pathology caused by the appearance of gas emboli in the bloodstream and tissues. However, the weak correlation between the amount of venous gas emboli (VGE) and the development of DCS, as well as the considerable interindividual variability in DCS susceptibility, suggests that a higher DCS resistance could be associated with a better management of VGE-induced stress. To study the effects of VGE independently of the hyperbaric stress induced by diving, Wistar and DCS-resistant male and female rats received 5 mL/kg of a 0.9% NaCl solution containing air microbubbles through the tail vein. After 120 min, the liver and lungs were harvested. Wet-to-dry weight ratio was determined in the lungs. Gene expression was quantified by reverse transcription-polymerase chain reaction in the liver. Compared with standard Wistar, DCS-resistant rats exhibited a lower lung wet-to-dry weight ratio after air microbubble injection, suggesting lower pulmonary fluid accumulation. In the liver, DCS-resistant rats showed higher tissue factor transcription at the basal state and post-air microbubble injection. Tissue factor pathway inhibitor was lower in DCS-resistant rats at the basal state but higher following air microbubble injection. Levels of heat shock protein 70 (HSP70), heat shock protein 27 (HSP27), and early growth response 1 (Egr-1) were higher in DCS-resistant rats after air microbubble injection. At the basal state, only HSP27 was higher in DCS-resistant rats, with HSP70 lower and Egr-1 not different. These results help clarify the pathways involved in the response to VGE and highlight potential mechanisms underlying resistance to DCS, including enhanced anticoagulant pathways and improved cellular stress responses.NEW & NOTEWORTHY This study suggests for the first time that DCS resistance may be associated with a better tolerance to VGE. This greater DCS resistance could be achieved through improved control of the procoagulant effects of bubbles via TFPI-dependent inhibitory mechanisms and an enhanced cellular stress response to VGE by HSP70, HSP27, and EGR-1. It also suggests that it may be possible to stratify the individual DCS risk based on the thromboinflammatory response to bubbles.