TY - JOUR
T1 - Activation of apoptosis by Salmonella pathogenicity island-1 effectors through both intrinsic and extrinsic pathways in Salmonella-infected macrophages
AU - Lin, Hsin Hung
AU - Chen, Hsiu Ling
AU - Weng, Chang Ching
AU - Janapatla, Rajendra Prasad
AU - Chen, Chyi Liang
AU - Chiu, Cheng Hsun
N1 - Publisher Copyright:
© 2020
PY - 2021/8
Y1 - 2021/8
N2 - Background: Salmonella enterica serovar Typhimurium, a non-typhoidal food-borne pathogen, causes acute enterocolitis, bacteremia, extraintestinal focal infections in humans. Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2) contribute to invading into host cellular cytosol, residing in Salmonella-containing vacuoles for intracellular survival, and inducing cellular apoptosis. This study aimed to better understand the mechanism underlying apoptosis in Salmonella-infected macrophages. Methods: S. Typhimurium SL1344 was used to evaluate extrinsic and intrinsic apoptosis pathways in THP-1 monocyte-derived macrophages in response to Salmonella infection. Results: Activated caspase-3-induced apoptosis pathways, including extrinsic (caspase-8-mediated) and intrinsic (caspase-9-mediated) pathways, in Salmonella-infected macrophages were verified. THP-1 cells with dysfunction of TLR-4 and TLR-5 and Salmonella SPI-1 and SPI-2 mutants were constructed to identify the roles of the genes associated with programmed cell death in the macrophages. Caspase-3 activation in THP-1 macrophages was induced by Salmonella through TLR-4 and TLR-5 signaling pathways. We also identified that SPI-1 structure protein PrgH and effectors SipB and SipD, but not SPI-2 structure protein SsaV, could induce apoptosis via caspase-3 activation and reduce the secretion of inflammation marker TNF-α in the Salmonella-infected cells. The two effectors also reduced the translocation of the p65 subunit of NF-κB into the nucleus and the expression of TNF-α, and then inflammation was diminished. Conclusion: Non-typhoid Salmonella induced apoptosis of macrophages and thereby reduced inflammatory cytokine production through the expression of SPI-1. This mechanism in host–pathogen interaction may explain why Salmonella usually manifests as occult bacteremia with less systemic inflammatory response syndrome in the bloodstream infection of children.
AB - Background: Salmonella enterica serovar Typhimurium, a non-typhoidal food-borne pathogen, causes acute enterocolitis, bacteremia, extraintestinal focal infections in humans. Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2) contribute to invading into host cellular cytosol, residing in Salmonella-containing vacuoles for intracellular survival, and inducing cellular apoptosis. This study aimed to better understand the mechanism underlying apoptosis in Salmonella-infected macrophages. Methods: S. Typhimurium SL1344 was used to evaluate extrinsic and intrinsic apoptosis pathways in THP-1 monocyte-derived macrophages in response to Salmonella infection. Results: Activated caspase-3-induced apoptosis pathways, including extrinsic (caspase-8-mediated) and intrinsic (caspase-9-mediated) pathways, in Salmonella-infected macrophages were verified. THP-1 cells with dysfunction of TLR-4 and TLR-5 and Salmonella SPI-1 and SPI-2 mutants were constructed to identify the roles of the genes associated with programmed cell death in the macrophages. Caspase-3 activation in THP-1 macrophages was induced by Salmonella through TLR-4 and TLR-5 signaling pathways. We also identified that SPI-1 structure protein PrgH and effectors SipB and SipD, but not SPI-2 structure protein SsaV, could induce apoptosis via caspase-3 activation and reduce the secretion of inflammation marker TNF-α in the Salmonella-infected cells. The two effectors also reduced the translocation of the p65 subunit of NF-κB into the nucleus and the expression of TNF-α, and then inflammation was diminished. Conclusion: Non-typhoid Salmonella induced apoptosis of macrophages and thereby reduced inflammatory cytokine production through the expression of SPI-1. This mechanism in host–pathogen interaction may explain why Salmonella usually manifests as occult bacteremia with less systemic inflammatory response syndrome in the bloodstream infection of children.
KW - Apoptosis
KW - Caspase-3
KW - Inflammatory cytokine
KW - Macrophage
KW - Salmonella pathogenicity island-1
KW - Salmonella typhimurium
UR - http://www.scopus.com/inward/record.url?scp=85080072294&partnerID=8YFLogxK
U2 - 10.1016/j.jmii.2020.02.008
DO - 10.1016/j.jmii.2020.02.008
M3 - 文章
C2 - 32127288
AN - SCOPUS:85080072294
SN - 1684-1182
VL - 54
SP - 616
EP - 626
JO - Journal of Microbiology, Immunology and Infection
JF - Journal of Microbiology, Immunology and Infection
IS - 4
ER -
