Effects of antiorthostatic suspension, tetanus toxoid, and CpG on the bone marrow antibody repertoire in C57BL/6 mice

Abstract

Abstract Each B cell produces an antibody composed of two heavy chains paired with two light chains. During development, B cells rearrange V-, D- (heavy chain only), and J-gene segments. These rearrangements along with the imprecisions in recombination and mutations create diversity in the antibody repertoire. The physical and psychological stressors of spaceflight are known to affect both the innate and adaptive immune systems. We used a ground-based model, antiorthostatic suspension (AOS), to analyze the impact of spaceflight environmental stressors on the antibody repertoire. Eight-week-old female C57BL/6J mice were suspended for two weeks and immunized via ip injection with saline, tetanus toxoid (TT) and/or CpG, and resuspended. Two weeks after immunization, animals were sacrificed, and bone marrow was collected. RNA was extracted and sequenced using MiSeq 2×300bp. Resulting sequences were analyzed using ImMunoGeneTic’s High-V quest program to identify antibody characteristics. We identified significant variations in VH, Vκ, D, JH, and Jκ-gene segment usage and CDR3 length due to AOS, TT, and CpG treatment. Changes were also detected in the class-switched repertoire for VH-gene segment usage. We also focused our analysis on the loaded saline, loaded TT+CpG, and AOS+TT+CpG treatment groups to isolate the TT-specific antibody response. Statistically significant changes were detected in VH-gene segment usage and gene segment combinations among treatment groups. These results demonstrate that treatment with a physiological model of spaceflight leads to alterations in the development of the TT-specific antibody repertoire in the bone marrow.