IL17A and osteoporosis: Despite the fact that the expression levels of IL-10 and IL-17α in the colon (Fig. 5b) were impacted in a way that has been shown to favor the development of osteoporosis (32, –, 34), serum levels of TNF-α and T cell populations in the bone marrow compartment were not impacted by the presence of a microbiota (Fig. 3).