1. Rheumatology/AIR, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden, Division of Molecular Physics, Department of Physics, Biology and Chemistry, Linköping University, Linköping, Sweden, Occupational and Environmental Medicine, Sahlgrenska University Hospital, Göteborg University, Göteborg, Sweden, and Medical Microbiology, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden