Biomarkers of cell and tissue injury in analog microgravity
- Paper number
IAC-05-A1.P.17
- Author
Dr. Alamelu Sundaresan, Texas Southern University, United States
- Coauthor
Dr. Anil Kulkarni, The University of Texas Health Science center, Medical School and Graduate School of Biomedical Sciences, United States
- Coauthor
Dr. Neal R. Pellis, National Aeronautics and Space Administration (NASA)/Johnson Space Center, United States
- Coauthor
Dr. Keiko Yamauchi, United States
- Year
2005
- Abstract
Introduction: Immune suppression in microgravity has been documented for many years. With human exploration and long-term space travel, the immune system of the astronaut has to be optimally maintained. Individual risks to organs, such as the heart, bone, muscle and the immune system occur in microgravity. In order to isolate biomarkers of organ injury in an " in vivo"analog microgravity model, the hind limb unloading model {HU} was utilized. Gene expression was the method of choice to isolate pertinent biomarkers of injury from splenocytes. Methods: Mice matched for age were hindlimb suspended {accepted analog microgravity model} for one week, along with control 1g mice. They were sacrificed after one week of hind limb suspension. Splenocytes were isolated, washed with Phosphate Buffered Saline and preserved in RNA lysis buffer. Messenger RNA was collected and subjected to gene array analysis using the Affymetrix HG_U95 mouse array. Data was collected and subjected to a two-way analysis of variance. Genes related to different kinds of organ and tissue injury were analyzed. Results and Conclusions: Detailed analysis of the murine splenocytes revealed that there was a pronounced increase in biomarkers of cardiovascular injury, such as PIGF {placental induced growth factor} in HU splenocytes {5-fold increase compared with 1g housed mice-90%, confidence interval}. Within the past three years, PIGF has gained impetus as a specific biomarker for cardiovascular injury in comparison to C-reactive protein {C-RP}, which has proven to be more of a general marker for inflammation. Another gene of interest which had a similar upward shift was Syk {Spleen tyrosine kinase} (6-fold increase in HU splenocytes compared with control-90% confidence interval). The spleen tyrosine kinase {Syk} and the CD3-{zeta}-associated PTK (ZAP-70) define a new one, the Syk family. ZAP-70 appears to be expressed exclusively in T cells and NK cells, whereas Syk is preferentially expressed in B cells, T cells, and myeloid cells. Syk is an important enzyme in various inflammation pathways relevant to respiratory diseases such as asthma. Knowledge of the expression levels of these molecules in high stress environments such as microgravity, high altitude and other specialized aviation exercises, is essential for the development of intervention strategies. The careful study of adaptational responses in both human and closely related mammalian systems will help identify targets and propose prophylactic measures and interventions for prolonged space exploration.
- Abstract document
- Manuscript document
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