Figure 1

From Mortensen[29]with permission: summary of the dynamic interplay between A. baumannii and the host. (1) A. baumannii can adhere and invade host cells, leading to stimulation of the pro-inflammatory immune response. (2) The inflammatory response is initiated by TLR4 recognition of LPS which then activates MAPK and NF-κB pathways. TLR2 is also reported to detect A. baumannii. (3) Activation of these receptor proteins leads to subsequent transcription and secretion of pro-inflammatory mediators such as cytokines IL-6 and TNF-α and chemokines KC/IL-8 and MIP-2. (4) These chemokines recruit granulocytes and lymphocytes that are required for controlling infection. (5) Following A. baumannii infection host cells also undergo apoptosis. (6) Other host defences include nutritional immunity, ROS/RNS production, and antimicrobial peptides. (7) In response to the host environment, A. baumannii expresses several virulence factors implicated in pathogenesis, which are displayed in the inset of the figure. The illustration depicts those proteins and molecules that are functionally characterized and those that are predicted to be expressed. The question marks designate areas in which there are significant gaps in our knowledge.