A novel Pseudomonas aeruginosa-derived effector cooperates with flagella to mediate the upregulation of interleukin 8 in human epithelial cells

• Nucleoside diphosphate kinase (Ndk) is a novel Pseudomonas aeruginosa-derived product.
• Ndk is involved in the expression of chemokine IL-8 upon translocated into host cells.
• The induction is dependent on the presence of flagella via the NF-κB signaling pathway.

Infection with Pseudomonas aeruginosa results in a massive accumulation of neutrophils in response to prolonged and sustained expression of inflammatory mediators. The major chemokine associated with this excessive neutrophil recruitment is IL-8, the accumulation of which is a hallmark of cornea and cystic fibrosis airway inflammation. To date, several P. aeruginosa-associated and extracellular factors required for the stimulation of IL-8 expression have been identified. Here, we report a novel effector molecule, nucleoside diphosphate kinase (Ndk), which increases the expression of IL-8 by translocating into host cells. The induction appears to be dependent on both the kinase activity of Ndk and an additional bacterial factor, flagellin, via an NF-κB signaling pathway. This study demonstrates the role of a novel effector, Ndk, which is capable of inducing prominent inflammatory chemokine IL-8 expression with the aid of flagellin during P. aeruginosa infection.