Listeriolysin O Pore-Forming Activity Is Required for ERK1/2 Phosphorylation During Listeria monocytogenes Infection

Cui, Cheng; Sun, Jing; Yu, Huifei; Ma, Tiantian; Guan, Chiyu; Zeng, Huan; Zhang, Xian; Chen, Zhongwei; Song, Houhui

doi:10.3389/fimmu.2020.01146

Cited by 15 publications

(12 citation statements)

References 51 publications

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“…To further establish the role of Salmonella OmpA against the cytosolic nitrosative stress of macrophages, we have ectopically expressed listeriolysin O (LLO) in wild-type Salmonella Typhimurium. The intracellular population of Listeria monocytogenes, a causative agent of listeriosis, utilizes LLO to degrade the phagosomal membrane for escaping lysosomal fusion [28,55]. Expressing LLO in wild-type Salmonella will force the bacteria to quit the SCV and be released into the cytosol with intact OmpA on their outer membrane.…”

Section: Discussionmentioning

confidence: 99%

SalmonellaTyphimurium outer membrane protein A (OmpA) renders protection against nitrosative stress by promoting SCV stability in murine macrophages

Sah

Varshney

et al. 2021

Preprint

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Porins are highly conserved bacterial outer membrane proteins having β barrel structure and are majorly involved in the selective transport of charged molecules across the membrane. Despite having huge contributions in the pathogenesis of many gram-negative bacteria, their role remains elusive in salmonellosis. In this study, we have characterized the pathogenic role of porins majorly found on the outer membrane of Salmonella Typhimurium (such as OmpA, OmpC, OmpD, and OmpF) paying the utmost importance to OmpA. The outer membrane protein A (OmpA) of Salmonella Typhimurium has shown a multifaceted role in our study. We have observed that deletion of ompA from wildtype Salmonella has made it more prone to phagocytosis and weakly proliferative in macrophages. Whereas, in epithelial cells STM ΔompA was found to be invasion deficient and hyper-proliferative. The poor colocalization of STM ΔompA with LAMP-1 confirmed impaired stability of SCV membrane around the intracellular bacteria, which further resulted in the release of the knockout strain to the cytosol of macrophage where it is bombarded with reactive nitrogen intermediates (RNI). The cytosolic localization of STM ΔompA was found to be responsible for the downregulation of SPI-2 encoded virulent factor SpiC which is required for suppressing the activity of iNOS. The reduced recruitment of nitrotyrosine on wildtype Salmonella staying in the cytosol of macrophage by ectopically expressing Listeriolysin O (LLO) strongly proves the pro-bacterial role of OmpA against host nitrosative stress. The time-dependent increase in 405/ 488 ratio of STM ΔompA pQE60-Grx1-roGFP2 exposed to in vitro acidified nitrite suggested RNI dependent redox burst which further answered the reason for its enhanced sensitivity towards nitrosative stress. Our study further demonstrated loss of integrity and enhanced porosity in the bacterial outer membrane in absence of OmpA. The enhanced porosity of the bacterial outer membrane was further attributed to the upregulated expression of larger porins namely ompC, ompD, and ompF. In comparison with STM ΔompA ΔompC and ΔompA ΔompF, the enhanced uptake of nitrite and greater recruitment of nitrotyrosine on intracellular STM ΔompA ΔompD demonstrate the involvement of OmpC and OmpF in the entry of excess nitrite in ompA deficient bacteria.

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Section: Discussionmentioning

confidence: 99%

SalmonellaTyphimurium outer membrane protein A (OmpA) renders protection against nitrosative stress by promoting SCV stability in murine macrophages

Sah

Varshney

et al. 2021

Preprint

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“…VPA decrease MC cytokine production by these TLR2 ligands, in similar way to what is observed in macrophages stimulated with Pam 22 . In addition, we observed that VPA inhibited MC activation with LLO, which activates MC in a TLR2-independent manner 14 , 30 through cholesterol dependent activation 36 mediated by ERK1/2 phosphorylation 49 . These observations indicate that VPA does not affect TLR2 expression in MC and suggest that this compound compromises L.m-mediated MC activation by modulating intracellular activation mechanisms involved in the MC response to this pathogen.…”

Section: Discussionmentioning

confidence: 76%

Valproic acid restricts mast cell activation by Listeria monocytogenes

Soria-Castro

Meneses-Preza

Rodríguez-López

et al. 2022

Sci Rep

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Mast cells (MC) play a central role in the early containment of bacterial infections, such as that caused by Listeria monocytogenes (L.m). The mechanisms of MC activation induced by L.m infection are well known, so it is possible to evaluate whether they are susceptible to targeting and modulation by different drugs. Recent evidence indicates that valproic acid (VPA) inhibits the immune response which favors L.m pathogenesis in vivo. Herein, we examined the immunomodulatory effect of VPA on L.m-mediated MC activation. To this end, bone marrow-derived mast cells (BMMC) were pre-incubated with VPA and then stimulated with L.m. We found that VPA reduced MC degranulation and cytokine release induced by L.m. MC activation during L.m infection relies on Toll-Like Receptor 2 (TLR2) engagement, however VPA treatment did not affect MC TLR2 cell surface expression. Moreover, VPA was able to decrease MC activation by the classic TLR2 ligands, peptidoglycan and lipopeptide Pam3CSK4. VPA also reduced cytokine production in response to Listeriolysin O (LLO), which activates MC by a TLR2-independent mechanism. In addition, VPA decreased the activation of critical events on MC signaling cascades, such as the increase on intracellular Ca2+ and phosphorylation of p38, ERK1/2 and -p65 subunit of NF-κB. Altogether, our data demonstrate that VPA affects key cell signaling events that regulate MC activation following L.m infection. These results indicate that VPA can modulate the functional activity of different immune cells that participate in the control of L.m infection.

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“…Continuing with this observation, STM ΔompA , staying in the cytosol of macrophages, showed greater colocalization with nitrotyrosine compared to the wild-type bacteria protected inside the SCV. The intracellular population of Listeria monocytogenes utilizes LLO to degrade the phagosomal membrane for escaping lysosomal fusion [ 34 , 70 ]. A decreased recruitment of nitrotyrosine on the cytosolic population of STM (WT): LLO and their better survival compared to STM ΔompA and ΔompA : LLO showed the role of OmpA in defending the cytosolic population of Salmonella from the harmful effect of RNI.…”

Section: Discussionmentioning

confidence: 99%

Salmonella Typhimurium outer membrane protein A (OmpA) renders protection from nitrosative stress of macrophages by maintaining the stability of bacterial outer membrane

et al. 2022

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Bacterial porins are highly conserved outer membrane proteins used in the selective transport of charged molecules across the membrane. In addition to their significant contributions to the pathogenesis of Gram-negative bacteria, their role(s) in salmonellosis remains elusive. In this study, we investigated the role of outer membrane protein A (OmpA), one of the major outer membrane porins of Salmonella, in the pathogenesis of Salmonella Typhimurium (STM). Our study revealed that OmpA plays an important role in the intracellular virulence of Salmonella. An ompA deficient strain of Salmonella (STM ΔompA) showed compromised proliferation in macrophages. We found that the SPI-2 encoded virulence factors such as sifA and ssaV are downregulated in STM ΔompA. The poor colocalization of STM ΔompA with LAMP-1 showed that disruption of SCV facilitated its release into the cytosol of macrophages, where it was assaulted by reactive nitrogen intermediates (RNI). The enhanced recruitment of nitrotyrosine on the cytosolic population of STM ΔompAΔsifA and ΔompAΔssaV compared to STM ΔsifA and ΔssaV showed an additional role of OmpA in protecting the bacteria from host nitrosative stress. Further, we showed that the generation of greater redox burst could be responsible for enhanced sensitivity of STM ΔompA to the nitrosative stress. The expression of several other outer membrane porins such as ompC, ompD, and ompF was upregulated in STM ΔompA. We found that in the absence of ompA, the enhanced expression of ompF increased the outer membrane porosity of Salmonella and made it susceptible to in vitro and in vivo nitrosative stress. Our study illustrates a novel mechanism for the strategic utilization of OmpA by Salmonella to protect itself from the nitrosative stress of macrophages.

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Listeriolysin O Pore-Forming Activity Is Required for ERK1/2 Phosphorylation During Listeria monocytogenes Infection

Cited by 15 publications

References 51 publications

SalmonellaTyphimurium outer membrane protein A (OmpA) renders protection against nitrosative stress by promoting SCV stability in murine macrophages

SalmonellaTyphimurium outer membrane protein A (OmpA) renders protection against nitrosative stress by promoting SCV stability in murine macrophages

Valproic acid restricts mast cell activation by Listeria monocytogenes

Salmonella Typhimurium outer membrane protein A (OmpA) renders protection from nitrosative stress of macrophages by maintaining the stability of bacterial outer membrane

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