MedicalResearch.com Interview with: Dr. Jean-Pol Frippiat Stress, Immunity and Pathogens Laboratory Lorraine University Vandoeuvre-lès-Nancy, France  What is the background for this study? What are the main findings? Dr. Frippiat: Osteoporosis is associated to spaceflight. Consequently, we wondered whether changes in bone micro-structure induced by a ground-based model of spaceflight, hindlimb unloading (HU) that simulates some of the effects of spaceflight on mice, induces changes in B lymphocyte production in the bone marrow. To this end, we analyzed both bone parameters and the frequency of cells of the B lineage in the bone marrow of young, old and HU mice. We found that HU leads to a decrease in both bone micro-structure and the frequency of B cell progenitors in the bone marrow. A major block at the pro-B to pre-B cell transition was observed indicating a decrease in the formation of B cells in the bone marrow. Interestingly, the modifications in B cell production were similar to those observed in aged mice. These findings demonstrate that mechanical unloading, to which astronauts are subjected during spaceflight, results in a decrease in B cell differentiation that resemble age-related modifications in B lymphopoiesis. (more…)