An Analysis of the Effects of Spaceflight and Vaccination on Antibody Repertoire Diversity

Hindlimb unloading, a physiological model of microgravity, modifies the murine bone marrow IgM repertoire in a similar manner as aging but less strongly

BACKGROUND

The spaceflight environment is an extreme environment that affects the immune system of approximately 50% of astronauts. With planned long-duration missions, such as the deployment of the Lunar Gateway and possible interplanetary missions, it is mandatory to determine how all components of the immune system are affected, which will allow the establishment of countermeasures to preserve astronaut health. However, despite being an important component of the immune system, antibody-mediated humoral immunity has rarely been investigated in the context of the effects of the space environment. It has previously been demonstrated that 30 days aboard the BION-M1 satellite and 21 days of hindlimb unloading (HU), a model classically used to mimic the effects of microgravity, decrease murine B lymphopoiesis. Furthermore, modifications in B lymphopoiesis reported in young mice subjected to 21 days of HU were shown to be similar to those observed in aged mice (18-22 months). Since the primary antibody repertoire composed of IgM is created by V(D) J recombination during B lymphopoiesis, the objective of this study was to assess the degree of similarity between changes in the bone marrow IgM repertoire and in the V(D)J recombination process in 2.5-month-old mice subjected to 21 days of HU and aged (18 months) mice.

RESULTS

We found that in 21 days, HU induced changes in the IgM repertoire that were approximately 3-fold less than those in aged mice, which is a rapid effect. Bone remodeling and epigenetics likely mediate these changes. Indeed, we previously demonstrated a significant decrease in tibial morphometric parameters from day 6 of HU and a progressive reduction in these parameters until day 21 of HU, and it has been shown that age and microgravity induce epigenetic changes.

CONCLUSION

These data reveal novel immune changes that are akin to advanced aging and underline the importance of studying the effects of spaceflight on antibody-mediated humoral immunity.

Immune repertoire analysis of normal Chinese donors at different ages

OBJECTIVES

This study investigated the characteristics of the immune repertoire in normal Chinese individuals of different ages.

MATERIALS AND METHODS

In this study, all seven receptor chains from both B and T cells in peripheral blood of 16 normal Chinese individuals from two age groups were analyzed using high-throughput sequencing and dimer-avoided multiplex PCR amplification. Normal in this study is defined as no chronic, infectious or autoimmune disease within 6 months prior to blood draw.

RESULTS

We found that compared with the younger group, the clonal expression of T-cell receptor repertoire increased in the older group, while diversity decreased. In addition, we found that the T-cell receptor repertoire was more significantly affected by age than the B-cell receptor repertoire, including significant differences in the use of the unique TCR-alpha and TCR-beta V-J gene combinations, in the two groups of normal participants. We further analyzed the degree of complementarity determining region 3 sequence sharing between the two groups, and found shared TCR-alpha, TCR-gamma, immunoglobulin-kappa and immunoglobulin-lambda chain complementarity determining region 3 sequences in all subjects.

CONCLUSION

Taken together, our study gives us a better understanding of the immune repertoire of different normal Chinese people, and these results can be applied to the treatment of age-related diseases. Immune repertoire analysis also allows us to observe participant's wellness, aiding in early-stage diagnosis.