Open AccessDifferential Immune Responses to Segniliparus rotundus and Segniliparus rugosus Infection and Analysis of Their Comparative Virulence Profiles
Author(s) -
Jong Seok Kim,
Woo Sik Kim,
Keehoon Lee,
Choul Jae Won,
JinMan Kim,
Seok Yong Eum,
Won Jung Koh,
Sung Jae Shin
Publication year - 2013
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0059646
Subject(s) - immune system , biology , tlr2 , innate immune system , immunology , macrophage , microbiology and biotechnology , inflammation , signal transduction , tumor necrosis factor alpha , genetics , in vitro
Two closely related bacterial species, Segniliparus rotundus and Segniliparus rugosus , have emerged as important human pathogens, but little is known about the immune responses they elicit or their comparative pathophysiologies. To determine the virulence and immune responses of the two species, we compared their abilities to grow in phagocytic and non-phagocytic cells. Both species maintained non-replicating states within A549 epithelial cells. S. rugosus persisted longer and multiplied more rapidly inside murine bone marrow-derived macrophages (BMDMs), induced more pro-inflammatory cytokines, and induced higher levels of macrophage necrosis. Activation of BMDMs by both species was mediated by toll-like receptor 2 (TLR2), followed by mitogen-activated protein kinases (MAPK) and nuclear factor κB (NF-κB) signaling pathways, indicating a critical role for TLR2 in Segniliparus -induced macrophage activation. S. rugosus triggered faster and stronger activation of MAPK signaling and IκB degradation, indicating that S. rugosus induces more pro-inflammatory cytokines than S. rotundus. Multifocal granulomatous inflammations in the liver and lung were observed in mice infected with S. rugosus , but S. rotundus was rapidly cleared from all organs tested within 15 days post-infection. Furthermore, S. rugosus induced faster infiltration of innate immune cells such as neutrophils and macrophages to the lung than S. rotundus . Our results suggest that S. rugosus is more virulent and induces a stronger immune response than S. rotundus .