On the cover: The SEM image has been pseudocolored to depict presumed Staphylococcus aureus (golden) on the surface of an orthopedic titanium implant in vivo to model biofilm growth. The implant surface is extensively coated with a matrix material of unknown origin (original magnification ×20,000). Heim, C. E., D. Vidlak, T. D. Scherr, J. A. Kozel, M. Holzapfel, D. E. Muirhead, and T. Kielian. 2014. Myeloid-derived suppressor cells contribute to S. aureus orthopedic biofilm infection. J. Immunol. 192: 3778–3792.