Identification of the molecular mechanism of Klebsiella pneumoniae NTUH K2044-induced NETs formation and liver abscess
Klebsiella pneumoniae is an important pathogen causing community-acquired infections such as pneumonia and community-acquired pyogenic liver abscess (PLA). When encountered bacterial infection, neutrophils could engulf and kill the bacteria either by phagocytosis or form neutrophil extracellular traps (NETs) to bind and kill pathogens extracellularly. In this study, the K. pneumoniae NTUH-K2044 strain could induce NETs formation in vitro. Analysis of the genome of NTUH-K2044 strain revealed this strain harbors putative type VI secretion system (T6SS)-encoding genes which likely account for the host and pathogen interaction. Deletion of T6SS effector and structural proteins-encoding genes of the NTUH-K2044 all significantly reduced the activity of NETs formation. The PLA-associated K. pneumoniae utilized the T6SS-mediated competition to establish infection in mice. The NTUH-K2044 strain deleted for the T6SS genetic loci was profoundly attenuated in virulence as demonstrated in the mouse model of septicemia. These results obtained from this study will help us to understand the pathogenic mechanism of T6SS in K. pneumoniae and might identify potential targets for therapeutic design.