A Novel Caspase-1/Toll-like Receptor 4-independent Pathway of Cell Death Induced by Cytosolic Shigella in Infected Macrophages

Suzuki, Toshihiko; Nakanishi, Kenji; Tsutsui, Hiroko; Iwai, Hiroki; Akira, Shizuo; Inohara, Naohiro; Chamaillard, Mathias; Núñez, Gabriel; Sasakawa, Chihiro

doi:10.1074/jbc.m414671200

Cited by 55 publications

(57 citation statements)

References 51 publications

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Section: Introductionmentioning

confidence: 99%

“…While this cell death pathway is clearly dependent on caspase-1, it shows features of both apoptosis and necrosis (Haimovich & Venkatesan, 2006). Finally, S. flexneri can also induce a caspase-1-and IpaB-independent cell-death pathway, which is triggered by bacterial LPS (lipid A) delivered to the macrophage cytoplasm (Suzuki et al, 2005).Here, we provide evidence that in S. flexneri-infected macrophages the translocator/effector protein IpaB is intracellularly secreted over a prolonged time, during which the bacterial pool is gradually depleted. To test the effect of CCCP (Sigma) on the growth of S. flexneri, the protonophore (25 mM) was added 2 h after inoculation, and 2.5 h later the bacteria were centrifuged and resuspended in TSB medium with or without 25 mM CCCP.…”

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confidence: 99%

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Intracellular type III secretion by cytoplasmic Shigella flexneri promotes caspase-1-dependent macrophage cell death

2007

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The Gram-negative bacterium Shigella flexneri triggers pro-inflammatory apoptotic cell death in macrophages, which is crucial for the onset of an acute inflammatory diarrhoea termed bacillary dysentery. The Mxi-Spa type III secretion system promotes bacterial uptake and escape into the cytoplasm, where, dependent on the translocator/effector protein IpaB, caspase-1 [interleukin (IL)-1b-converting enzyme] and its substrate IL-1b are activated. Here, we show that in the course of a macrophage infection, IpaB is secreted intracellularly for more than 1 h post-infection and progressively accumulates in aggregates on the bacterial surface. Concomitantly, the bacterial pool of IpaB is gradually depleted. The protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) dose-dependently inhibited the Mxi-Spa-dependent secretion of IpaB triggered by the dye Congo red in vitro and abolished translocation of IpaB into the host-cell cytoplasm of S. flexneri-infected macrophages. CCCP specifically inhibited S. flexneri-triggered macrophage death in a dose-dependent manner, even if added up to 60 min post-infection. Addition of CCCP 15 min after infection blocked macrophage cell death, the activation of caspase-1 and the maturation of IL-1b, without affecting uptake or escape of S. flexneri from the phagosome. By contrast, CCCP used at the same concentration had no effect on ATP-induced caspase-1 activation or staurosporine-induced apoptosis. Our results indicate that under the conditions used, CCCP rapidly and specifically blocks bacterial type III secretion, and thus, intracellular type III secretion promotes cytotoxicity of S. flexneri. INTRODUCTIONMany symbiotic or pathogenic Gram-negative bacteria employ a type III secretion system (T3SS) to establish a replicative niche (Cornelis, 2006;Galan & Wolf-Watz, 2006). The complex T3SSs are evolutionarily related to flagellar secretion systems and composed of a basal structure spanning the two bacterial membranes, a hollow needle (or pilus/filament) and a hydrophobic translocator complex inserted into eukaryotic target membranes. Some T3SSs deliver more than 20 different 'effector' proteins into target cells, where they subvert cellular functions in favour of the bacteria. In the eukaryotic host cells, the bacterial effectors target phosphoinositide metabolism, GTP cycles, phosphoprotein signalling, cytoskeletal and vesicle dynamics, or apoptotic pathways (Cossart & Sansonetti, 2004;Hilbi, 2006;Rosenberger & Finlay, 2003;Schlumberger & Hardt, 2006). Shigella flexneri, the causative agent of a severe diarrhoea termed bacillary dysentery (shigellosis), employs a T3SS to invade non-phagocytic epithelial cells and to kill macrophages (Cossart & Sansonetti, 2004). The S. flexneri T3SS is encoded by the mxi and spa genes on the 214 kb virulence plasmid (Buchrieser et al., 2000). Investigations by electron microscopy revealed that the Mxi-Spa needle complex is a canonical T3SS composed of a basal body and a needle, the major subunit of which (MxiH) is required for the secretion of eff...

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Intracellular type III secretion by cytoplasmic Shigella flexneri promotes caspase-1-dependent macrophage cell death

2007

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“…Shigella multiply in the cytoplasm and induce cell death through activation of caspase-1 mediated by IpaB protein secreted via the type III secretion system, in turn leading to the maturation and release of IL-1␤ (5, 6). However, our recent work has shown that macrophages undergo proinflammatory necrotic cell death, and that the necrosis and caspase-1 activation are due to components common to Gram-negative bacteria (7). Another group has reported that Ipaf, a member of the pathogen-associated molecular pattern-sensing Nod family proteins, is implied a role in caspase-1 activation in Shigella-infected macrophages (8).…”

Section: High Vaccine Efficacy Against Shigellosis Of Recombinant Nonmentioning

confidence: 99%

“…Previous studies have shown that intracytosolic Shigella that have escaped from phagosomes induce death of the infected macrophages and dendritic cells (7,42), and that components common to Gram-negative bacteria induce necrotic cell death and caspase-1 activation (7). Mouse J774 macrophages were infected with wildtype Shigella, ⌬virG (conventional attenuated vaccine strain), ⌬ipaB, and ⌬ipaB/inv to determine whether ⌬ipaB/inv was capable of inducing cell death.…”

Section: Generation and Characterization Of An Invasin-expressing Shimentioning

confidence: 99%

High Vaccine Efficacy against Shigellosis of Recombinant Noninvasive Shigella Mutant That Expresses Yersinia Invasin

Suzuki

Yoshikawa

Ashida

et al. 2006

The Journal of Immunology

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Live attenuated Shigella vaccines elicit protective immune responses, but involve a potential risk of inducing a strong inflammatory reaction. The bacterial invasiveness that is crucial for Ag delivery causes inflammatory destruction of infected epithelial cells and proinflammatory cell death of infected macrophages. In this study, the noninvasive Shigella mutant ΔipaB was equipped with Yersinia invasin protein, which has been shown to mediate bacterial invasion and targeting to M cells located in follicle-associated epithelium. Invasin-expressing ΔipaB (ΔipaB/inv) was internalized into epithelial cells and retained in the intraphagosomal space. ΔipaB/inv did not induce necrotic cell death of infected macrophages nor cause symptomatic damage after intranasal vaccination of mice. ΔipaB/inv was safer and more effective than the conventional live vaccine, ΔvirG. Infection by ΔipaB/inv caused polymorphonuclear neutrophil infiltration in the lung, but did not induce production of large amounts of proinflammatory cytokines. We concluded that the low experimental morbidity and high vaccine efficacy of ΔipaB/inv are primarily based on high protective immune responses, which may be enhanced by the polymorphonuclear neutrophil infiltration unaccompanied by tissue injury.

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“…Shigella invade resident macrophages in the lamina propria, and the bacteria escape from the phagosome into the cytosol. Infected macrophages undergo caspase-1-mediated cell death, termed pyroptosis, that is a newly identified pathway of programmed cell death associated with an inflammatory response, [12][13][14] but the precise mechanisms remain poorly understood.…”

Section: Introductionmentioning

confidence: 99%

A role for Nod-like receptors in autophagy induced byShigellainfection

Suzuki

Núñez²

2008

Autophagy

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Shigella infection, the cause of bacillary dysentery, induces caspase-1 activation and cell death in macrophages, but the precise mechanisms remain poorly understood. In our recent study, we presented evidence that caspase-1 activation and IL-1β processing induced by Shigella are mediated through Ipaf, a cytosolic patternrecognition receptor of the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family and the adaptor protein apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC). We also show that Ipaf and caspase-1 were critical for pyroptosis, a specialized form of caspase-1-dependent cell death induced in macrophages by bacterial infection, whereas ASC is dispensable. Notably, infection of macrophages with Shigella induced autophagy, which was dramatically increased by the absence of caspase-1 or Ipaf, but not ASC. Furthermore, autophagy induction was associated with transient resistance to pyroptosis. These results indicate that autophagy in macrophages is regulated by the Ipaf inflammasome, providing a novel function for NLR proteins in bacterial-host interactions.

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A Novel Caspase-1/Toll-like Receptor 4-independent Pathway of Cell Death Induced by Cytosolic Shigella in Infected Macrophages

Cited by 55 publications

References 51 publications

Intracellular type III secretion by cytoplasmic Shigella flexneri promotes caspase-1-dependent macrophage cell death

Intracellular type III secretion by cytoplasmic Shigella flexneri promotes caspase-1-dependent macrophage cell death

High Vaccine Efficacy against Shigellosis of Recombinant Noninvasive Shigella Mutant That Expresses Yersinia Invasin

A role for Nod-like receptors in autophagy induced byShigellainfection

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