Background - Abnormally regulated apoptosis and circulating apoptotic signal, such as pro-apoptotic mediator Fas ligand (FasL), were found in several pathologies, including heart disorders, cancer and pulmonary hypertension (PH). Yet, almost nothing is known about the expression profile and biomarker properties of FasL in the circulation of human beings during acute and chronic exposure to high altitude (HA) environment.
Methods - In order to investigate the presence and potential biomarker attributes of FasL, we have measured the plasma values of FasL using enzyme-linked immunosorbent assay in Kyrgyz volunteers exposed to acute (n=7-8) and chronic effects (n=9-10) of HA milieu.
Results - We have found that there was a prominent reduction of FasL in the blood of lowland subjects exposed to HA environment. In addition, decreased circulatory levels of FasL were demonstrated in highlanders with HA-induced PH (HAPH), in comparison to the lowland controls. Finally, there was a negative correlation between the FasL concentration in plasma and tricuspid regurgitant gradient values.
Conclusion - Therefore, we have described for the first time that circulating levels of FasL were decreased in human subjects exposed to acute and chronic effects of HA environment. Furthermore, FasL may serve as a promising biomarker in the future for patients with HAPH.