Potential protein markers associated with the functional state of vessels prior to long-term space missions and on the first post-landing day

The impact of the long-term space missions on the blood filling of the vessels appears to be a serious issue for the medical team. The goal of our work is to analyze the blood proteome composition in order to detect signaling molecules, controlling the functional state of astronauts blood vessels before space mission and on the first day as they return. Blood samples were taken from 13 male cosmonauts (mean age ± SD: 44 ± 6 yrs) who participated in 169–199 day missions for the Russian International space station. Blood flow was determined using the methods of electrocardiography, impedance cardiography and photoplethysmography. Proteomic analysis involved liquid chromatography - tandem mass spectrometry (LC-MS/MS). A panel of labeled internal standards was used to target quantitative analysis of 125 extracellular matrix proteins. Of the total list, five proteins associated directly with the vessels vasodilation (haptoglobin, vasorin, complement component С4В, vitamin D-binding protein and paraoxonase 3) showed differences between the two groups of cosmonauts. According to the proteomic data analysis, vasorin and complement component C4 which effects on the vascular blood filling of the vessels, had similar trends during acute re-adaptation after landing. The Level of haptoglobin increased in the group with low vascular blood filling and was stable in the group with high vascular blood in the vessels. Whereas vitamin D-binding protein and paraoxanase 3, their post-landing variability increased in both groups; however, the inter-group differences defined before launch retained. In our opinion, these proteins might be biomarkers of the processes associated with arteries blood filling in the vessels for both the public and cosmonauts in the period of acute re-adaptation on return from long-term missions.