Impact of high-altitude exposure on Torque Teno virus and immunosuppression levels in lung transplantation recipients: climbing Mount Jebel Toubkal

Following lung transplantation (LuTx), some patients attain good long-term health, enabling participation in demanding activities, including high-altitude mountaineering. High-altitude exposure induces substantial physical stress through hypoxia, exhaustion and ultraviolet (UV) radiation, potentially compromising immunocompetence. Levels of immunosuppression and Torque Teno virus (TTV), a persistent, non-pathogenic DNA virus associated with immunocompetence after LuTX, were measured during an expedition to Mount Jebel Toubkal (4167 m), evaluating the effects of high-altitude exposure, physical exertion and UV radiation. Immunosuppression levels were evaluated in 14 LuTx recipients and compared to those of 12 healthy controls through TTV quantification before, during and after the expedition. A microsampling device (MSD) was validated in the cohort by comparing capillary blood samples with EDTA plasma samples to enable measurements in remote areas. Immunosuppression levels were determined using liquid chromatography–tandem mass spectrometry, and TTV DNA was quantified using real-time polymerase chain reaction. TTV DNA was detectable in 13 LuTx recipients (92.8%) and 10 healthy controls (83.3%). The LuTx recipients had significantly higher baseline TTV loads than the healthy controls ( p = < 0.0001), and the female recipients exhibited significantly higher TTV loads than their male counterparts ( p = 0.047). The TTV levels remained stable throughout the expedition and weeks afterward in both LuTx recipients ( p = 0.998) and healthy controls ( p = 0.852). The average TTV load was 1.27 log 10 copies/mL lower in the MSD than in the EDTA plasma. The tacrolimus and everolimus trough levels remained stable during the expedition ( p = 0.326 and 0.894, respectively). Eleven LuTx recipients reached the summit without any adverse events, proving extreme physical exertion, even at high altitudes, safe for selected patients. The stable immunosuppressive drug trough levels and TTV loads indicate good tolerance relative to physical stress. MSDs represent a valuable tool for monitoring TTV and immunosuppressive drug trough levels in remote or resource-limited settings.