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The interest in the role of the gravitational factor during landing after long-term space flights (SF) leads to the search for various innovative approaches to assessing the compliance of external changes observed by clinicians. The results of special research methods such as Omics technologies that may reflect physiological responses to the conditions created during landing are of great interest. Our purpose is to compare the blood plasma proteome changes associated with the trauma and endothelial dysfunction processes prior to launch and on the day of landing, as well as the groups of cosmonauts with and without the secondary hemorrhagic purpura. In our study, the concentrations of 125 plasma proteins in 18 Russian cosmonauts, measured using targeted proteomic analysis based on liquid chromatography and tandem mass spectrometry were analyzed. The results reveal the trends of 12 proteins participating in the processes that trigger hemorrhagic purpura under the effect of re-entry g-forces. Exposure to intense g-forces and return to the gravity are the key factors for external manifestations of changes in the body systems induced by a long-term stay in space microgravity. Our results may be useful for further research to experts in gravitational physiology, aviation and space medicine.

The effect of the rapid redistribution of blood during head-up tilt tests in 21-day Dry Immersion suddenly became relevant in connection with the occurrence of mild hemorrhagic syndrome in the study participants. It became necessary to analyze the processes of occurrence of hemorrhagic syndrome as orthostatic and congestive purpura. The aim of this work was to study the features of the proteomic response of the human body to the rapid redistribution of blood during head-up tilt tests during 21-day immersion, which led to stagnant and orthostatic purpura. According to the results of examination of 10 healthy male volunteers aged 23–34 years after head-up tilt tests, pitting edema and local petechial hemorrhages in the soft tissues of the legs and feet were observed. Proteomic analysis of the samples was carried out by high performance liquid chromatography with tandem mass spectrometry. For bioinformatic analysis, the software packages Perseus, ANDSystem were used. From reliably different (p-value

The proteome of human umbilical vein endothelial cells (HUVEC) cultured under static conditions and simulated microgravity (sμG) using Random Positioning Machine (RPM) for 24 h was studied by chromatography-mass spectrometry. It was revealed that the percentage of ribosomal proteins and proteins involved in intercellular adhesion, regulation of actin cytoskeleton, various pathways of cell signaling mediated by G-proteins, apoptosis and ubiquitin-dependent protein catabolism increased under sμG. At the same time the number of proteins associated with cell growth reduced. A significant increase in the peak intensities of proteins associated with maintaining the cytoskeleton and stress fibers (myristoylated alanine-rich C-kinase substrate, filamin-A, alpha-actinin-1 and myosin light polypeptide 6) and proteins involved in response to unfolded protein (serpin H1, 78 kDa glucose-regulated protein, transitional endoplasmic reticulum ATPase) was shown. At the same time, a significant decrease in the peak intensity of cofilin 1, which is capable of breaking actin filaments, was revealed. Thus, the most pronounced effect of microgravity is on the proteins associated with the actin cytoskeleton, as well as on adhesion proteins, whose properties also depend on the structure of the cytoskeleton. At the same time, the number of proteins which prevent improper protein folding increases, and the translation apparatus is rearranged under sμG.

The prospects of interplanetary missions make it relevant to develop standard tests to find criteria for the correction of preventive measures in a long space flight in order to ensure a peak in physical performance by the time the interplanetary activity is completed. Currently, tests are being developed to assess physical performance. One of them can be the currently developed locomotor test with a stepwise increasing load in the active mode of movement of the treadmill. It is of interest to assess the effect of this load on changes in the profile of proteins associated with the cardiovascular system from the standpoint of the possibility of using them as markers of its response to physical activity. In article analyzes the results of an experimental study of the proteome of human urine after a dosed step-increasing load and discusses the possible role of the identified proteins that can be attributed to the functioning of the cardiovascular system. The study involved practically healthy volunteers aged 18.6 ± 0.7 years, weighing 75.7 ± 8 kg (n = 12). The urine proteome was evaluated by chromatography-mass spectrometry and analyzed by bioinformatics methods. For the first time, data on the proteomic response to a locomotor test with a stepwise increasing load in the active mode of web movement in a group homogeneous in autonomic status are presented. As a result of the analysis, 429 proteins were identified, 69 of which significantly changed. Based on bioinformatics analysis, processes related to the work of the heart, vascular tone, and vascular permeability were identified. Ten proteins are described that are associated with the processes of the quick response of the cardiovascular system to dosed physical activity. The obtained results will help in choosing standard criteria for assessing the physiological cost of physical activity.

Under controlled conditions of 17-day isolation (Sirius-17 experiment), the protein composition of urine was studied in 6 healthy test volunteers-3 women and 3 men. Collection of samples in the form of a second freely separated morning urine fraction was carried out in the background (seven days before the experiment), as well as 1 day after the end of exposure. Chromatographic-mass-spectrometric semi-quantitative analysis of the protein composition of samples was performed on a system consisting of an Agilent 1100 chromatograph and an LTQ-FT Ultra hybrid mass spectrometer using bioinformatics resources UniProtKB, GeneOntology. An asymptomatic change in the immune defense system of kidney tissue after isolation in a closed hermetic object is associated with a change in the content of 7 proteins that provide functional activity of the TLR tubules of the kidneys - FcRIII, MUC1, Galectin-3, Ficolin-2, APOA1, FLNA, FCGR3A and Clusterin. These proteins are found to be useful biomarkers in the study of physiology and kidney diseases. They can be attributed to candidates for protein markers of the initial stages of impaired recognition by the epithelium of renal tubules of bacteria with known pathogenic potential.

Study of changes in the proteome of extracellular body fluids under conditions of simulated weightlessness of medium duration (21 days) remains relevant for clarifying the physiological mechanisms of homeostasis regulation and is important for gravitational physiology and medicine. Plasma samples of 8 healthy volunteers participating in head down bed rest (HDBR –6°) experiment were studied using semi-quantitative proteomics methods. Each volunteer participated both in the control session and in the session with physical training for negative changes prevention. By the end of HDBR, significant changes in the concentration of proteins involved in platelet degranulation, blood coagulation, fibrinolysis, proteolysis regulation, complement activation, and the immune response were detected in both sessions. The following changes in biochemical parameters of carbohydrate metabolism and regulation of circulating blood volume were shown: a significant increase in renin concentration and a tendency to an increase in aldosterone; an increase in fasting insulin concentration and a tendency to an increase in the insulin resistance index. Physical training did not have a significant effect on biochemical parameters, except for the representation of cholesterol fractions, un which a significant decrease in the concentration of high-density lipoprotein cholesterol observed in HDBR became statistically insignificant in session with physical training. However, the protein composition in blood plasma of volunteers in the prophylaxis session changed less compared to HDBR. Physical training resulted in increase in the concentration of proteins involved in the normalization of carbohydrate and lipid metabolism, such as a macrophage stimulating protein and phosphatidylinositol-glycan-specific phospholipase D, which indicates the effectiveness of preventive measures.

The purpose of this work was to reveal the intra- and inter-individual variability of the urine proteomic composition and of biochemical blood parameters in cosmonauts with different preflight autonomic status when they are back to Earth (on the 1st and 7th day after space flight). The objects of the study were 5-min samples of electrocardiogram (ECG) at rest and urine and venous blood samples, obtained in the same timeline from twelve male cosmonauts (age 46.5 ± 3.4 years), who performed space flights (SF) with duration 169–199 days onboard the Russian segment of the International Space Station (ISS). Two groups with different sympathetic-parasympathetic balance were identified (each consists of 6 cosmonauts) by the results of preflight heart rate variability (HRV) analysis. We have revealed in groups of cosmonauts with preflight predominance of sympathetic or parasympathetic tone the significant differences in the directionality of changes on days 1 and 7 after the SF as compared to the preflight values in three proteins (from total amount around 200): alpha-1 subunit of collagen type VI, Mucin 1, Cadherin-13. A set of biochemical parameters, unidirectionally changing with these proteins, was different in classified groups. Direct bilirubin, potassium and total calcium move unidirectionally with collagen, direct bilirubin, potassium – with mucin, and uric acid, ferrum, alpha-1, KFK, potassium - with cadherin in group with a sympathetic tone. Potassium, ferrum, alpha-1 move unidirectionally with collagen, amylase, KFK, AST, urea, inorganic phosphate, glucose, alkaline phosphatase, ionized calcium – with mucin, and total ferrum biding capacity, transferrin, glucose gamma globulin transferase - with cadherin in group with parasympathetic predominance. Probably, differences between groups in the concentration of these proteins and their different relationship with some biochemical parameters reflect different ways to achieve the same goal - adaptation to a complex of SF factors and re-adaptation after returning to Earth.

Urine chromatography–mass spectrometry and a heart rate variability (HRV) analysis were performed in 13 healthy males (age 28 ± 4 years, height 174 ± 1 cm, weight 67.9 ± 1.5 kg). Mathematical and bioinformatics analyses identified the proteins that are associated with the condition of the cardiovascular system and the autonomic regulation of the heart rate in the total protein aggregate. The set included serotransferrin, tyrosine-protein kinase receptor UFO, prostatic acid phosphatase, secreted and transmembrane protein 1, cell adhesion molecule 4, galectin-3-binding protein, immunoglobulin heavy constant alpha 1, matrix remodeling-associated protein 8, and biotinidase. Associations were for the first time studied for protein markers of the heart rate autonomic regulation. Proteomics data were used to describe the indicators of the heart rate physiological regulation in the urine proteome of healthy young males.

We performed the first ever comparative analysis of modifications in the proteome, ionogram and some other blood plasma biochemical indices of 18 male cosmonauts (44 ± 6 years of age) before and after maiden or repeated long-term missions to the Russian segment of the International space station (ISS RS). Levels of proteins, substrates and ions as well as chemical components were measured using the LC-MS-based proteomics and routine biochemical techniques. A total of 256 to 281 indices were investigated with the methods of descriptive statistic, regression analysis, and access to bioinformatics resources. It was shown that blood indices recovery from the maiden and repeated missions reflects changes in the body systems and goes at a various speed. The results of measurements made prior to launch and on day 7 after landing are dependent on the number of missions. The bioinformatics techniques showed that after maiden missions both the mediator proteins of alkaline phosphatase (AP) and blood proteins with reliably changing concentrations are associated with the bio-processes including stress, metabolism and DNA reparation, apoptosis, catabolism and proteolysis. During early re-adaptation from repeated missions the AP level was affected by bone remodeling, phosphorylation, angiogenesis and coagulation cascade suggesting a distinct and urgent trigger of the processes of bone structure and mineralization.

The study presents the results of evaluating the changes in the concentrations of blood plasma proteins associated with heart rate variability in cosmonauts who have completed space missions lasting about 6 months. The concentrations of 121 proteins were quantified in biological samples of the cosmonauts' blood plasma. The subgroups of proteins associated with the physiological processes of the heart rate variability autonomic regulation were identified using bioinformatic resources (Immunoglobulin heavy constant mu, Complement C1q subcomponent subunit C, Plasma serine protease inhibitor, Protein - 72 kDa type IV collagenase, Fibulin-1, Immunoglobulin lambda constant 3). The concentration of these proteins in the blood plasma before the flight, and the dynamics of concentration changes on the 1st and 7th days of the post-flight rehabilitation period differed in the groups of cosmonauts with a predominance of sympathetic or parasympathetic modulating autonomous influences. The dynamics of changes in the concentrations of the identified set of proteins reveal that in cosmonauts with a predominance of sympathetic modulating influences, the mechanisms of autonomic regulation are exposed to significant stress in the recovery period immediately after the completion of the space mission, compared with the cosmonauts with a predominance of parasympathetic modulating influences.

On the basis of proteomics, modern data on the features of bone remodeling in astronauts after long-term space flights are presented. We describe the regulatory proteins of the blood proteome that are significantly associated with bone remodeling processes. By analyzing large amounts of data, we for the first time determined associations of signaling proteins that are process regulators characterizing new steps of bone remodeling in astronauts during the acute period of readaptation after landing.

In order to find markers to assess the functional state of the cardiovascular system (CVS) before and after spaceflight (first and seventh day after landing), we analyzed the urine proteome composition of 10 Russian cosmonauts aged of 35–51 years who have completed 169–199-day spaceflight onboard the International Space Station (ISS). Also an analysis of urine samples of 6 cosmonaut back-ups was conducted. A special sample preparation was performed, followed by liquid chromatography-mass spectrometry. It was shown that after long duration space flight concentration of several proteins of CVS in urine samples varies significantly. The dynamic of presence in urine of thioredoxin and apolipoprotein A-I could be related to the spaceflight, as it were not found before flight and in back-up controls, but were detected after the spaceflight. It was found that changes in cosmonauts’ urine proteome comprehensively reflect the adaptive responses of cardiovascular, renal and neuroendocrine systems to long-duration microgravity conditions. The use of bioinformatics analysis to the reconstruction of protein-protein interaction networks and the identification of overrepresented Gene Ontology (GO) biological processes related to the cardiovascular system allowed us to establish relationships between proteomic data and physiological effects observed in cosmonauts after the flight. Hypotheses on the possible pathogenesis and etiological factors causing this adaptive response were suggested in this work.

Background The conditions of space flight have a significant effect on the physiological processes in the human body, yet the molecular mechanisms driving physiological changes remain unknown. Methods Blood samples of 18 Russian cosmonauts who had conducted long-duration missions to the International Space Station were collected 30 days before launch and on the first and seventh days after landing. Results A panel of 125 proteins in the blood plasma was quantitated by a well-established and highly regarded targeted mass spectrometry approach. This method involves the monitoring of multiple reactions in conjunction with stable isotope-labeled standards at the University of Victoria - Genome BC Proteomics Centre. Conclusions Reduction of circulating plasma volume during space flight and activation of fluid retention at the final stage of the flight affect the changes in plasma protein concentrations present in the first days after landing. Using an ANOVA approach, it was revealed that only 1 protein (S100A9) reliably responded to space flight conditions. This protein plays an important role in the functioning of the endothelium and can serve as a marker for activation of inflammatory reactions. Concentrations of the proteins of complement, coagulation cascades, and acute phase reactants increase in the blood of cosmonauts as measured the first day after landing. Most of these proteins’ concentrations continue to increase by the 7th day after space flight. Similar dynamics are observed for proteases and their inhibitors. Thus, there is a shift in proteolytic blood systems, which is necessary for the restoration of muscle tissue and maintenance of oncotic homeostasis. Electronic supplementary material The online version of this article (10.1186/s12920-019-0490-y) contains supplementary material, which is available to authorized users.

Spaceflight (SF) conditions have a significant impact on the functioning of the human cardiovascular system. The endothelium plays an important role in the process of adaptation to SF factors. Therefore, the detection of biomarkers of endothelial dysfunction is necessary for understanding the molecular mechanisms involved in changes caused by SFs. For this purpose, the blood plasma proteins of 18 Russian cosmonauts were used for quantitative analysis by liquid chromatography with a UPLC 1290 Infinity chromatograph coupled to an Agilent 6490 triple quadrupole mass spectrometer. It was found that a decrease in the circulating plasma volume during the flight followed by the activation of fluid retention at the final stage of flight contributed to the changes in plasma protein concentrations on the first day after landing. We observed a significant increase in the concentration of the S100A9 protein that plays an important role in endothelium functioning and angiogenesis and can serve as a marker of inflammatory reactions. On the first day after landing, the complement system and acute-phase protein concentrations tended to increase, which can adversely affect the functioning of the endothelium.

The study of proteins - potential markers, associated signal transduction pathways, and their targets - provides a new understanding of the fundamental mechanisms occurring at the level of regulatory processes in the cardiovascular system (CVS), especially in space flight, as well as in model experiments that reproduce its individual effects on the human body. The article presents the results of studies in an experiment with 120-day isolation within the framework of the SIRIUS project in which 6 volunteers aged 28 to 44 years (three men and three women) participated. SIRIUS (Scientific International Research in Unique Terrestrial Station) is the international research project, which studies the issues of biomedical and psychological support of long-term manned space flights. The possible involvement of collagen different types, an extracellular matrix protein, in the mechanisms of autonomic regulation of the CVS was studied. Using chromatic mass spectrometry in urine samples and analysis of heart rate variability, we have established that the extracellular matrix collagen, which is present, in particular, in the structure of the blood vessel wall, are markers associated with the modulating effect of the autonomic nervous system on the regulatory mechanisms of blood circulation. We hypothesized that these proteins may be a biomarker of the autonomic balance in the regulatory mechanisms of the circulatory system. In addition, these proteins can also be markers of the aging process, which increases the risks of developing autonomic dysfunction of the cardiovascular system (dominance of sympathicotonia) and changes in the quality of the tissue of the heart muscle and blood vessels, provoking the development of prenosological conditions and diseases of the cardiovascular system.

For the first time proteins are described, reliably increasing and decreasing in urine with age in the range of 20 to 60 years. The combinations of proteins associated with changes in immune processes, violation of blood reology, including the risk of coagulopathy, anticancer defense mechanisms, insulin signaling pathway, changes in cell characteristics are characterized division and quality of the newly formed fabric. Thus, the age dynamics of the main processes triggers a cascade of reactions manifested in the closure of «pathological biochemical circles» that form the prerequisites for the development of diseases and, over time, clinical manifestations.Впервые описаны белки, достоверно увеличивающиеся и уменьшающиеся в моче с возрастом в интервале 20–60 лет. Охарактеризованы комбинации белков, связанных с изменением иммунных процессов, нарушением реологии крови, в том числе риском коагулопатии, противоопухолевых защитных механизмов, инсулинового сигнального пути, с изменением характеристик клеточного деления и качества новообразованной ткани. Таким образом, возрастная динамика основных процессов запускает каскад реакций, проявляющихся в замыкании «патологических биохимических кругов», которые формируют предпосылки к развитию заболеваний и, с течением времени, клинические проявления.

The purpose of the study was to investigate the regulatory and metabolic changes in the circulatory system when simulating microgravity conditions in a five-day dry immersion. These changes reflect the adaptation processes characteristic for the initial stages of a space flight or a short-duration space flight. Studies were conducted with 13 healthy male volunteers aged 21 to 29 years. The assessment of regulatory and metabolic processes in the circulatory system was based on the heart rate variability (HRV) and urine proteomic profile analysis. It was found that the restructuring of hemodynamics during 5 days hypogravity begins with the inclusion of the nervous circuit of regulation, and for manifestations at the body fluids protein composition level and activation of the metabolic regulation, these periods are apparently insufficient. Perhaps this is due to the fact that the metabolic regulation, being evolutionarily ancient and genetically determined, is more stable and requires more time for its pronounced activation when stimulated by extreme life conditions.

We performed liquid chromatography-mass spectrometric study of the urine proteome in 8 healthy volunteers aged between 20 and 44 y.o. who have completed 21-day head-down bed rest. ANDSystem software which builds associative networks was used to identify the urinary proteins functionally related to the endothelium. We identified 7 endothelium-related biological processes, directly linked to 13 urine proteins. We performed manual annotation of the proteins which were the most important in terms of endothelial functions. Analysis of the correlations with biochemical variables revealed a positive correlation between fasting blood glucose and the following urine proteins: albumin, CD44 antigen, endothelial protein C receptor, mucin-1, osteopontin, receptor tyrosine kinase. As well, we found a positive correlation between HOMA-insulin resistance index and the following urine proteins: endothelial protein C receptor and syndecan-4. These results might suggest the involvement of above-mentioned proteins in glucose metabolism and their participation in the response to changes in blood glucose level.

In our study urine protein composition of 18 healthy volunteers was compared with that of 18 patients with ischemic heart disease and concomitant hypertension. Liquid chromatography-mass-spectrometry (LC-MS) analysis of the second fraction of morning urine was carried out using nano-line high performance liquid chromatograph and hybrid mass spectrometer. The analysis revealed 23 proteins expressed in the endothelium, according to the information contained in the database Bgee, and 49 proteins, with direct functional link with the processes in the endothelium in the reconstruction of associative networks using ANDSystem program. Comparison of urine proteome of healthy people and patients with postinfarction cardiosclerosis revealed proteins specific for patients with cardiovascular disease. Thus, proteins vitronectin, syndecan-4, a histidine rich glycoprotein, endothelial protein C receptor, colony stimulating factor, cathepsin D and sekretogranin-1 may be considered as potential markers for cardiovascular diseases. Further research in this area should be conducted for clinical and experimental verification of these hypotheses.

Background The strategy of adaptation of the human body in microgravity is largely associated with the plasticity of cardiovascular system regulatory mechanisms. During long-term space flights the changes in the stroke volume of the heart are observed, the heart rate decreases, the phase structure of cardiac cycle is readjusted The purpose of this work was to clarify urine proteome changes associated with the initial condition of the heart rate autonomic regulation mechanisms in cosmonauts who have participated in long space missions. Urine proteome of each cosmonaut was analyzed before and after space flight, depending on the initial parameters characterizing the regulatory mechanisms of the cardiovascular system. Results The proteins cadherin-13, mucin-1, alpha-1 of collagen subunit type VI (COL6A1), hemisentin-1, semenogelin-2, SH3 domain-binding protein, transthyretin and serine proteases inhibitors realize a homeostatic role in individuals with different initial type of the cardiovascular system regulation. The role of significantly changed urine proteins in the cardiovascular homeostasis maintenance is associated with complex processes of atherogenesis, neoangiogenesis, activation of calcium channels, changes in cell adhesion and transmembrane properties, changes in extracellular matrix, participation in protection from oxidative stress and leveling the effects of hypoxia. Therefore, the concentrations of these proteins significantly differ between groups with dominant parasympathetic and sympathetic influences. Conclusion The space flight induced urine proteome changes are significantly different in the groups identified by heart rate autonomic regulation peculiarities before space flight. All these proteins regulate the associated biological processes which affect the stiffness of the vascular wall, blood pressure level, the severity of atherosclerotic changes, the rate and degree of age-related involution of elastin and fibulin, age-related increase in collagen stiffness, genetically determined features of elastin fibers. The increased vascular rigidity (including the aorta) and of myocardium may be regarded as a universal response to various extreme factors. Significant differences in the semi-quantitative analysis of signal proteins between groups with different types of autonomic regulation are explained by a common goal: to ensure optimal adaptation regardless of age and of the genetically determined type of responses to the extreme environmental factors effects. Electronic supplementary material The online version of this article (10.1186/s12918-019-0688-9) contains supplementary material, which is available to authorized users.

Specifics of urine proteome is sensitive to a multitude of factors. One is nutrition or entrance in organism of main nutrients including salt (NaCI). Purpose of the investigation was to study the proteomic composition of healthy human urine in the controlled environment of a 105-day isolation experiment (projectMars-500) with various levels of salt intake. Analysis was performed using the present-day proteomics techniques based on chromatography-mass spectrometry and bio-informatics options. An attempt was made to correlate changes in processes and physiological systems with the controlled salt intake. As a result, a list of proteins directly responsible for different salt intake during the experiment and then a list of tissues where these proteins express predominantly were compiled; besides, analysis of the processes these proteins are involved in was performed.

The secretome of human umbilical vein endothelial cells (HUVEC) cultured under static conditions and in modeled microgravity for 24 h was studied by chromatography-mass spectrometry. In the secretome of cells exposed to microgravity, we identified a group of microtubule proteins including many structural elements of microtubules and regulatory proteins interacting with Rho-GTPases. Hence, reorganization of actin cytoskeleton and microtubules induced by microgravity is under complex regulation mediated by Rho proteins.

Clinical observation and examination of 12 patients with chronic pyelonephritis (CPN) were performed. The first group (GI) included patients with exacerbation of the disease. In the comparison group (GII)- the same patients after 1.5-3 months after completion of treatment, without clinical manifestations of exacerbation of CPN. Laboratory signs of acute renal damage were not revealed in all examined patients. Additionally, urine was collected in the afternoon after Breakfast, in the form of a freely separated 2nd fraction and its sample preparation, consisting of the stages: recovery, alkylation, protein deposition and proteolysis using trypsin. The resulting polypeptide mixture was separated by liquid chromatography in three repetitions and analyzed on a system consisting of Agilent 1100 chromatograph and ltq-FT ultra hybrid mass spectrometer. A list of proteins was obtained, indicating the number of peptides by which they were identified, and the parameters of its reliability. Most of the information about the obtained proteins was obtained from UniProt databases. Identified and analyzed 10 proteins that differ significantly in occurrence in the clinical group of patients in the period of exacerbation of PN. The appearance of these proteins in urine in 1patients with exacerbation of chronic PH allows us to consider them as potential biomarkers directly associated with inflammation and damage to the epithelial lining of the renal tubules.

Introduction: Spaceflight is one of the most extreme conditions encountered by humans: Individuals are exposed to radiation, microgravity, hypodynamia, and will experience isolation. A better understanding of the molecular processes induced by these factors may allow us to develop personalized countermeasures to minimize risks to astronauts.Areas covered: This review is a summary of literature searches from PubMed, NASA, Roskosmos and the authors’ research experiences and opinions. The review covers the available proteomic data on the effects of spaceflight factors on the human body, including both real space missions and ground-based model experiments.Expert commentary: Overall, the authors believe that the present background, methodology and equipment improvements will enhance spaceflight safety and support accumulation of new knowledge on how organisms adapt to extreme conditions.

The aim of the study was to compare proteomic data on the effects of spaceflight factors on the human body, including both real space missions and ground-based experiments. LC&ndash, MS/MS-based proteomic analysis of blood plasma samples obtained from 13 cosmonauts before and after long-duration (169&ndash, 199 days) missions on the International Space Station (ISS) and for five healthy men included in 21-day-long head-down bed rest (HDBR) and dry immersion experiments were performed. The semi-quantitative label-free analysis revealed significantly changed proteins: 19 proteins were significantly different on the first (+1) day after landing with respect to background levels, 44 proteins significantly changed during HDBR and 31 changed in the dry immersion experiment. Comparative analysis revealed nine common proteins (A1BG, A2M, SERPINA1, SERPINA3, SERPING1, SERPINC1, HP, CFB, TF), which changed their levels after landing, as well as in both ground-based experiments. Common processes, such as platelet degranulation, hemostasis, post-translational protein phosphorylation and processes of protein metabolism, indicate common pathogenesis in ground experiments and during spaceflight. Dissimilarity in the lists of significantly changed proteins could be explained by the differences in the dynamics of effective development in the ground-based experiments. Data are available via ProteomeXchange using the identifier PXD013305.