NOTE: End date changed to 9/30/2023 per NASA JSC. (Ed., 11/18/21)

NOTE: End date changed to 9/30/2022 per PI (Ed., 10/6/20)

NOTE: Extended to 3/31/2021 per PI (March 2019)--Ed., 10/3/19

The unique radiation environment encountered in space has been known to cause deleterious effects in humans, and these effects are of special concern for prolonged space missions beyond the protective terrestrial magnetosphere. DNA lesions, namely single- and double-strand breaks, are the most common of these effects and the most likely to compromise health. In addition to radiation, astronauts in space experience microgravity and other stress factors. In human cells, immune cells in particular, stress-induced catecholamine and corticoid release, as well as increased levels of inflammation, are known to induce DNA damage and impair DNA repair, which in turn results in single and double-strand breaks. Intact DNA repair machinery is crucial for immune cell functionality. Therefore understanding the interaction between DNA damage response and immune response is an important step towards improving knowledge of the mechanisms associated with immune dysfunction in the space environment.

In this study, we propose to quantify DNA damage in astronauts’ lymphocytes by measuring the frequency of single- and double-strand breaks. We will also perform RNA-seq analysis with a focus on pathways involved in DNA damage response and/or inflammatory response. Measures of DNA damage obtained before, during, and after long-duration International Space Station (ISS) missions will then be compared with the mRNA levels. The outcomes in the present study will also be compared to the measured T cell function, cytokine profiles and viral reactivation in the Integrated Immune Flight Study, which is the parental project of our proposed study.

In this study, blood samples from eleven crewmembers were collected before, during, and after International Space Station (ISS) missions. Transcriptomic and microRNA analyses were performed in isolated peripheral blood mononuclear cells (PBMCs) using RNA sequencing. Differentially expressed genes (DEGs) and microRNAs during spaceflight were identified by comparing inflight samples with preflight samples. In addition, DNA damage in astronauts’ lymphocytes was quantified by measuring the frequency of single- and double-strand breaks.

Through this study, we made the following key observations:

1. We propose that mitochondrial dysfunction in T cells during spaceflight is caused by persistent modulation of mechanosensing receptors under microgravity conditions, triggering signaling cascades that lead to mitochondrial calcium overload. The response of PBMCs in space exhibits features of T-cell exhaustion, which are more likely initiated by microgravity rather than infection.

2. We suggest that T cells from younger astronauts respond more strongly to the space environment than those from older astronauts, potentially resulting in greater negative immune consequences.

Although sample analysis has been completed, analysis of the collected data is still ongoing. Ongoing work includes the following:

1. Completion of the microRNA analysis and submission of a manuscript reporting these results.

2. Completion of the PCR analysis and submission of a manuscript reporting these results.

3. Completion of the gene expression-chromosomal location analysis and submission of a manuscript reporting these results.

4. Completion of the DNA damage analysis using PBMC samples.

5. Comparative analysis of gene expression data from this study with other immune function measurements by a NASA Johnson Space Center (JSC) biostatistician.

NOTE: End date changed to 9/30/2022 per PI (Ed., 10/6/20)

NOTE: Extended to 3/31/2021 per PI (March 2019)--Ed., 10/3/19

The unique radiation environment encountered in space has been known to cause deleterious effects in humans, and these effects are of special concern for prolonged space missions beyond the protective terrestrial magnetosphere. DNA lesions, namely single- and double-strand breaks, are the most common of these effects and the most likely to compromise health. In addition to radiation, astronauts in space experience microgravity and other stress factors. In human cells, immune cells in particular, stress-induced catecholamine and corticoid release, as well as increased levels of inflammation, are known to induce DNA damage and impair DNA repair, which in turn results in single and double-strand breaks. Intact DNA repair machinery is crucial for immune cell functionality. Therefore understanding the interaction between DNA damage response and immune response is an important step towards improving knowledge of the mechanisms associated with immune dysfunction in the space environment.

In this study, we propose to quantify DNA damage in astronauts’ lymphocytes by measuring the frequency of single- and double-strand breaks. We will also perform RNA-seq analysis with a focus on pathways involved in DNA damage response and/or inflammatory response. Measures of DNA damage obtained before, during, and after long-duration International Space Station (ISS) missions will then be compared with the mRNA levels. The outcomes in the present study will also be compared to the measured T cell function, cytokine profiles and viral reactivation in the Integrated Immune Flight Study, which is the parental project of our proposed study.

To date, collection of blood samples has been performed on 10 ISS crewmembers and 10 matching ground controls at all of the 7 (6 for ground controls) time points (L-180, L-45, mid-flight, late-flight, R+0, R+30, and R+90). Collection from the 11th crewmember and the ground control has not begun.

Sample analysis

RNA-seq analysis. Gene expression sample analysis using the RNA-seq technique was completed for 8 ISS crewmembers and 8 matching ground controls.

MicroRNA analysis. MicroRNA sample analysis using the RNA-seq technique was completed for 8 ISS crewmembers and 8 matching ground controls.

PCR analysis. Analysis of expression of DNA damage and immune function related genes using the PCR-array technique was completed for 4 ISS crewmembers and 4 matching ground controls. Supplies to analyse the next set of 4 crewmembers and ground controls have been purchased and received.

DNA damage analysis. DNA damage analysis is being performed at University of Konstanz, Germany.

Data analysis

RNA-seq data. Analysis of RNA-seq data was completed for 4 ISS crewmembers and 4 matching ground controls. Initial bioinformatics analysis of the next set of 4 crewmembers and 4 matching ground controls has begun.

MicroRNA data. Analysis of microRNA data was completed for 4 ISS crewmembers and 4 matching ground controls.

The unique radiation environment encountered in space has been known to cause deleterious effects in humans, and these effects are of special concern for prolonged space missions beyond the protective terrestrial magnetosphere. DNA lesions, namely single- and double-strand breaks, are the most common of these effects and the most likely to compromise health. In addition to radiation, astronauts in space experience microgravity and other stress factors. In human cells, immune cells in particular, stress-induced catecholamine and corticoid release, as well as increased levels of inflammation, are known to induce DNA damage and impair DNA repair, which in turn results in single and double-strand breaks. Intact DNA repair machinery is crucial for immune cell functionality. Therefore understanding the interaction between DNA damage response and immune response is an important step towards improving knowledge of the mechanisms associated with immune dysfunction in the space environment.

In this study, we propose to quantify DNA damage in astronauts’ lymphocytes by measuring the frequency of single- and double-strand breaks. We will also perform RNA-seq analysis with a focus on pathways involved in DNA damage response and/or inflammatory response. Measures of DNA damage obtained before, during, and after long-duration International Space Station (ISS) missions will then be compared with the mRNA levels. The outcomes in the present study will also be compared to the measured T cell function, cytokine profiles and viral reactivation in the Integrated Immune Flight Study, which is the parental project of our proposed study.

The unique radiation environment encountered in space has been known to cause deleterious effects in humans, and these effects are of special concern for prolonged space missions beyond the protective terrestrial magnetosphere. DNA lesions, namely single- and double-strand breaks, are the most common of these effects and the most likely to compromise health. In addition to radiation, astronauts in space experience microgravity and other stress factors. In human cells, immune cells in particular, stress-induced catecholamine and corticoid release, as well as increased levels of inflammation, are known to induce DNA damage and impair DNA repair, which in turn results in single and double-strand breaks. Intact DNA repair machinery is crucial for immune cell functionality. Therefore understanding the interaction between DNA damage response and immune response is an important step towards improving knowledge of the mechanisms associated with immune dysfunction in the space environment.

In this study, we propose to quantify DNA damage in astronauts’ lymphocytes by measuring the frequency of single- and double-strand breaks. We will also measure expression levels of 90 genes known to be involved in DNA damage response and/or inflammatory pathways. Measures of DNA damage obtained before, during, and after long-duration International Space Station (ISS) missions will then be compared with the mRNA levels of the selected genes. The outcomes in the present study will also be compared to the measured T cell function, cytokine profiles and viral reactivation in the Integrated Immune Flight Study, which is the parental project of our proposed study.