AUTHOR=Abu Khweek Arwa , Amer Amal 

TITLE=Replication of Legionella Pneumophila in Human Cells: Why are We Susceptible?

JOURNAL=Frontiers in Microbiology

VOLUME=1

YEAR=2010

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2010.00133

DOI=10.3389/fmicb.2010.00133

ISSN=1664-302X

ABSTRACT=<p><italic>Legionella pneumophila</italic> is the causative agent of Legionnaires’ disease, a serious and often fatal form of pneumonia. The susceptibility to <italic>L. pneumophila</italic> arises from the ability of this intracellular pathogen to multiply in human alveolar macrophages and monocytes. <italic>L. pneumophila</italic> also replicates in several professional and non-professional phagocytic human-derived cell lines. With the exception of the A/J mouse strain, most mice strains are restrictive, thus they do not support <italic>L. pneumophila</italic> replication. Mice lacking the NOD-like receptor Nlrc4 or caspase-1 are also susceptible to <italic>L. pneumophila</italic>. On the other hand, in the susceptible human hosts, <italic>L. pneumophila</italic> utilizes several strategies to ensure intracellular replication and protect itself against the host immune system. Most of these strategies converge to prevent the fusion of the <italic>L. pneumophila</italic> phagosome with the lysosome, inhibiting host cell apoptosis, activating survival pathways, and sequestering essential nutrients for replication and pathogenesis. In this review, we summarize survival mechanisms employed by <italic>L. pneumophila</italic> to maintain its replication in human cells. In addition, we highlight different human-derived cell lines that support the multiplication of this intracellular bacterium. Therefore, these <italic>in vitro</italic> models can be applicable and are reproducible when investigating <italic>L. pneumophila</italic>/phagocyte interactions at the molecular and cellular levels in the human host.</p>