<b><i>Salmonella</i></b> and Reactive Oxygen Species: A Love-Hate Relationship

Abstract

Salmonella enterica represents an enterobacterial species including numerous serovars that cause infections at, or initiated at, the intestinal epithelium. Many serovars also act as facultative intracellular pathogens with a tropism for phagocytic cells. These bacteria not only survive in phagocytes but also undergo de facto replication therein. Phagocytes, through the activities of phagocyte NADPH-dependent oxidase and inducible nitric oxide synthase, are very proficient in converting molecular oxygen to reactive oxygen (ROS) and nitrogen species (RNS). These compounds represent highly efficient effectors of the innate immune defense. Salmonella is by no means resistant to these effectors, which may stand in contrast to the host niches chosen. To cope with this paradox, these bacteria rely on an array of detoxification and repair systems. Combination these systems allows for a high enough tolerance to ROS and RNS to enable establishment of infection. In addition, salmonella possesses protein factors that have the potential to dampen the infection-associated inflammation, which evidently results in a reduced exposure to ROS and RNS. This review attempts to summarize the activities and strategies by which salmonella tries to cope with ROS and RNS and how the bacterium can make use of these innate defense factors.

Assaying Chlamydia pneumoniae persistence in monocyte-derived macrophages identifies schisandrin lignans as phenotypic switchers

“…The limited potency of azithromycin in clearing the cultures from bacteria implies to the presence of an antibiotic-tolerant subpopulation of bacterial and emphasizes the importance of including nonpermissive host cell lines in chlamydial susceptibility studies. Redox status and glutathione homeostasis have recently emerged as modulators for intracellular bacteria virulence 53, 57 , indicating that targeting cellular redox mechanisms may offer a means for inducing a phenotypic switch in pathogenic bacteria. The superiority of schisandrin C compared to azithromycin in its ability to eliminate both active and persistent bacteria in THP-1 macrophages highlights the potential of this strategy in anti-persister therapy, triggering future research on nonconventional antibacterials.…”

Assaying Chlamydia pneumoniae Persistence in Monocyte-Derived Macrophages Identifies Dibenzocyclooctadiene Lignans as Phenotypic Switchers

“…The presented data also indicates that these activities are linked to the suppression of macrophage glutathione pools by the lignans. Redox status and glutathione homeostasis have recently emerged as modulators for intracellular bacteria virulence [46,52], indicating that targeting cellular redox mechanisms may offer a means for inducing a phenotypic switch in pathogenic bacteria. The superiority of schisandrin C compared to azithromycin in its ability to eliminate both active and persistent bacteria in THP-1 macrophages highlights the potential of this strategy in anti-persister therapy, triggering future research on nonconventional antibacterials.…”

Insights into the Oxidative Stress Response of Salmonella enterica serovar Enteritidis Revealed by the Next Generation Sequencing Approach

“…Salmonella Enteritidis, one of the most important non-typhoidal Salmonella serovars from the public health and veterinary medicine perspectives [ 23 , 24 , 25 , 26 ], has developed a robust anti-oxidative response not only to survive endogenous oxidative stress [ 27 ] but also to survive exogenous stress imposed by a host [ 28 ] or environment [ 29 ]. In other words, for successful host invasion, intracellular proliferation and/or environmental survival, possession of an efficient oxidative stress response is one of the key physiological characteristics of this pathogen.…”