Oxidative Posttranslational Modifications of Blood Plasma Proteins of Cosmonauts after a Long-Term Flight: Part II

Oxidative damage to main cell components (DNA, lipids, and proteins) in the human body during a spaceflight (SF) is more intense than in normal conditions because of the imbalance between production and elimination of free radicals and reactive oxygen species. Proteomics methods were used to estimate the frequency of oxidative posttranslational modifications (PTMs) in blood plasma proteins from Russian participants in semi-annual flights to the ISS. The influence of oxidative PTMs detectable after a SF on functional features was considered for the protein groups that are involved in metabolism of the extracellular matrix (ECM), lipid metabolism, immune functions, and control of inflammation according to a bioinformatics analysis. The protein components of apolipoproteins (APOA1, APOA2, APOA4, APOL1, and APOE) showed excessive oxidation in post-flight samples as compared with their pre-flight state, suggesting distortion of their vasculoprotective properties. A twofold or greater increase in the intensity of oxidative modification was observed for chains of both membrane and secretory immunoglobulins (Igs). The composition of oxidized fragments in chains (κ, γ1, γ2, γ4, and µ) of constant Ig domains indicated that the effector or signaling functions of Igs might be altered. Structural components of the ECM and ECM-associated compounds found in the extracellular fluid are a complex molecular hub that links immune functions, vascular competencies, inflammation control, protease–antiprotease balance, and hemostasis. The components of this system were considered in their close relationship.