Long-term 2G exposure causes a reduction in cell number of mTECs.
(A) Flow cytometric analysis of thymic epithelial cells (TECs) in mice exposed to 2G for 14 days. Mice were exposed to 2 g gravity (2G) for 14 days or left under 1G (control). Vestibular apparatus are surgically disrupted in some mice (VL). TECs (CD45–TER119– EpCAM+) in total thymic cells were analyzed by staining with UEA-1-lectin, an mTEC marker, and CD80 antibody. Numbers in panels indicates percentage of each fraction. The percentages of UEA-1– CD80lo (containing cTECs), UEA-1+CD80high (mTEChi), and UEA-1+CD80low (mTEClo) cells among thymic stroma cells are summarized in right figures. “C” in graphs indicates 1G control. N = 6 each C, C with VL, and 2G with VL groups. N = 5 for 2G. NS indicates that the difference is not significant (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test). (B) Cell numbers of total TECs (CD45–TER119– EpCAM+), UEA-1– CD80lo TECs (containing cTECs), mTECs (UEA-1+), mTEChi (UEA-1+CD80high), and mTEClo (UEA-1+CD80low) in the thymus are summarized in figures. N = 6 each C, C with VL, and 2G with VL groups. N = 5 for 2G. The asterisks indicate statistical significance at *P < 0.05 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test).