TNFRSF11B and infection: We found significantly higher mRNA levels of osteoprotegerin (Opg, which together with Rankl is a key mediator of the OB–OC crosstalk and bone homeostasis [34]), bone morphogenetic protein 2 (Bmp2, which plays an important role in inducing the osteogenic differentiation of mesenchymal stem cells [35]), and secreted phosphoprotein 1 (Spp1, coding for osteopontin, a marker of late osteogenic differentiation involved also in infection [26,36]), in 3D- versus 2D-cultured cells.