New protein nanocages are designed bearing two functional proteins, gamma-carboxyglutamic acid of protein C (PC-Gla) and thrombin receptor agonist peptide (TRAP), and have an anti-septic response. These nanoparticles reduce sepsis-induced organ injury and septic mortality in vivo. Noting that there are currently no medications for severe sepsis, these results show that novel nanoparticles can be used to treat sepsis.