CX3CL1 and bacterial infectious disease: We systematically profiled host responses by measuring plasma biomarkers in pathways of innate immunity (IL-6, IL-8, IL-10, TNFR1, fractalkine, suppression of tumorigenicity-2 [ST-2]), alveolar epithelial injury (RAGE), endothelial injury (angiopoeitin-2), and response to bacterial infection (procalcitonin and pentraxin-3; ref. 3).