IL6 and infection: This study established single- and dual-species infection models, bacterial simultaneous and sequential infection models, and found that F. nucleatum could coaggregate with P. aeruginosa to synergistically invade into pulmonary epithelial cells and transiently resist P. aeruginosa-induced cytotoxic damage to amplify IL-6 and TNF-α associated inflammation in pulmonary epithelial cells simultaneously infected with P. aeruginosa and F. nucleatum.