Cells´ Flow and Immune Cell Priming under alternating g-forces in Parabolic Flight

Abstract

Gravitational stress in general and microgravity (µg) in particular are regarded as major stress factors responsible for immune system dysfunction in space. To assess the effects of alternating µg and hypergravity (hyper-g) on immune cells, the attachment of peripheral blood mononuclear cells (PBMCs) to adhesion molecules under flow conditions and the antigen-induced immune activation in whole blood were investigated in parabolic flight (PF). In contrast to hyper-g (1.8 g) and control conditions (1 g), flow and rolling speed of PBMCs were moderately accelerated during µg-periods which were accompanied by a clear reduction in rolling rate. Whole blood analyses revealed a “primed” state of monocytes after PF with potentiated antigen-induced pro-inflammatory cytokine responses. At the same time, concentrations of anti-inflammatory cytokines were increased and monocytes displayed a surface molecule pattern that indicated immunosuppression. The results suggest an immunologic counterbalance to avoid disproportionate immune responses. Understanding the interrelation of immune system impairing and enhancing effects under different gravitational conditions may support the design of countermeasures to mitigate immune deficiencies in space.

Guest Edited Collection: Gravitational biology and space medicine

“…The Guest Edited Collection ‘ Gravitational biology and space medicine ’ includes publications reporting on health concerns for astronauts and cosmonauts 14–16 during space missions, and physiological changes caused by short-term µ g 17 . Several studies investigating the impact of µ g on the behaviour and health of mice on the ISS were published in this Collection 18–23 , in addition to investigations at the cellular level in space 24 and in short-term µ g provided by PF maneuvers 25 . Moreover, cell studies in simulated (s-) µ g at ground-based facilities are included in this Collection 26–30 .…”

“…A PF study examined the attachment of peripheral blood mononuclear cells to adhesion molecules under flow conditions, and antigen-induced immune activation in whole blood 25 . The flow and rolling speed of cells were moderately accelerated during µ g periods, which were accompanied by a clear reduction in rolling rate.…”

The Impact of Spaceflight and Simulated Microgravity on Cell Adhesion

“…In addition, after short-duration spaceflight, the peripheral monocytes from astronauts showed no change in the number of cells but a significantly reduced expression of CD26L and major histocompatibility complex, class II, DR (HLA-DR), which are known regulators of cell adhesion between lymphocyte and endothelial cells [71]. Consistent with this finding, the ability of peripheral blood mononuclear cells to adhere to the ICAM-1 substrate was reduced under simulated microgravity and shear flow conditions in vitro [72]. Although the force from the blood flow plays a decisive role in the monocyte's adhesion cascade and initial capture with endothelial by selectins [73], the adhesion ability of immune cells and endothelial cells can also be impaired in microgravity.…”

Gravitational Influence on Human Living Systems and the Evolution of Species on Earth

“…Previous studies have indicated the changes in monocyte physiology during spaceflight, where it has been found that monocytes lose their ability to trap bacteria after 5 days under microgravity [36]. The effect of immunosuppression with respect to monocytes was confirmed by a later study, where it was found that circulating monocytes lost their ability to invoke an immune response after a parabolic flight, with alternating gravitational forces [37]. While monocytes presented activation markers under hypergravity and normal gravity it manifested immunosuppression-related surface markers [37].…”