Biology subjects

Planes, R.

Publications and source records attributed to Planes, R..

9 recordsLinked to original sources

bioRxiv2023

Leishmania infantum-exploited Nrf2 transcription factor as a virulence process to escape macrophage-driven ferroptosis-like leishmanicidal process

Macrophages are the main effector cells during Leishmania infection. They contribute to the detection and elimination of Leishmania spp. and may also promote parasite resilience. Here, we report that the activation of the transcription factor Nrf2 in macrophages plays a pivotal role in the progression of Leishmania infantum infection by controlling inflammation and redox balance of macrophages. We also highlight the involvement of NOX2/ROS axis in the early Nrf2 activation and subsequently of PGE2/EP2r signalling in the sustainment of Nrf2 activation upon L. infantum infection. Moreover, we establish macrophage-driven ferroptosis-like process as a cell death program of L. infantum and the protective effect of Nrf2 in macrophages against L. infantum death. Altogether, these results identify Nrf2 as a critical factor for the susceptibility of Leishmania infantum infection, highlighting Nrf2 as a promising pharmacological target for the development of new therapeutic approaches for the treatment of visceral leishmaniasis.

microbiology↗

bioRxiv2023

EEF2-inactivating toxins engage the NLRP1 inflammasome and promote epithelial barrier disruption upon Pseudomonas infection

The intracellular inflammasome complex have been implicated in the maladaptive tissue damage and inflammation observed in chronic Pseudomonas aeruginosa infection. Human airway and corneal epithelial cells, which are critically altered during chronic infections mediated by P. aeruginosa, specifically express the inflammasome sensor NLRP1. Here, together with a companion study, we report that the NLRP1 inflammasome detects Exotoxin A (EXOA), a ribotoxin released by P. aeruginosa Type 2 Secretion System (T2SS) during chronic infection. Mechanistically, EXOA-driven Eukaryotic Elongation Factor 2 (EEF2) ribosylation and covalent inactivation promotes ribotoxic stress and subsequent NLRP1 inflammasome activation, a process shared with other EEF2-inactivating toxins, Diphtheria Toxin and Cholix Toxin. Biochemically, irreversible EEF2 inactivation triggers ribosome stress-associated kinases ZAK- and P38-dependent NLRP1 phosphorylation and subsequent proteasome-driven functional degradation. Finally, Cystic Fibrosis cells from patients exhibit exacerbated P38 activity and hypersensitivity to EXOA-induced ribotoxic stress-dependent NLRP1 inflammasome activation, a process inhibited by the use of ZAK inhibitors. Altogether, our results show the importance of P. aeruginosa virulence factor EXOA at promoting NLRP1-dependent epithelial damage and identify ZAK as a critical sensor of virulence-inactivated EEF2. KEY POINTSO_LIP. aeruginosa induces NLRP1-dependent pyroptosis in human corneal and nasal epithelial cells C_LIO_LIP. aeruginosa Exotoxin A (EXOA) and other EEF2-inactivating bacterial exotoxins activate the human NLRP1 inflammasome C_LIO_LIEEF2 inactivation promotes ribotoxic stress response and ZAK kinase-dependent NLRP1 inflammasome activation. C_LIO_LIBronchial epithelial cells from Cystic Fibrosis patients show extreme sensitivity to ribotoxic stress-dependent NLRP1 inflammasome activation in response to Exotoxin A C_LIO_LIP38 and ZAK inhibition protects Cystic Fibrosis epithelial cell from EXOA-induced pyroptosis C_LI

immunology↗

bioRxiv2021

SARS-CoV-2 Envelope protein (E) binds and activates TLR2: A novel target for COVID-19 interventions

In this study, we present a molecular characterization of the interaction between the SARS-CoV-2 envelope protein E with TLR2. We demonstrated that E protein interacts physically with TLR2 receptor in a specific and dose-dependent manner. Furthermore, we showed that this interaction is able to engage TLR2 pathway as demonstrated by its capacity to activate NF-{kappa}B transcription factor and to stimulate the production of CXCL8 inflammatory chemokine in a TLR2-dependent manner. Furthermore, in agreement with the importance of NF-{kappa}B in TLR signaling pathway, we showed that the chemical inhibition of this transcription factor led to significant inhibition of CXCL8 production, while blockade of P38 and ERK1/2 MAP kinases resulted only in a partial CXCL8 inhibition. Overall, our findings suggest considering the envelope protein E as a novel target for COVID-19 interventions: (i) either by exploring the therapeutic effect of anti-E blocking/neutralizing antibodies in symptomatic COVID-19 patients, or (ii) as a promising non-Spike SARS-CoV-2 antigen candidate to include in the development of next generation prophylactic vaccines against COVID-19 infection and disease. ImportanceAlthough, the exact mechanisms of COVID-19 pathogenesis are unknown, recent data demonstrated that elevated levels of pro-inflammatory cytokines in serum is associated with enhanced disease pathogenesis and mortality. Thus, determining the molecular mechanisms responsible for inflammatory cytokine production in the course of SARS-CoV-2 infection could provide future therapeutic targets. In this context, to the best of our knowledge, our report is first to use a detailed molecular characterization to demonstrate that SARS-CoV-2 Envelope E protein binds to TLR2 receptor. Specifically, we showed that SARS-CoV-2 Envelope E protein binds to TLR2 in a direct, specific and dose-dependent manner. Investigating signalling events that control downstream activation of cytokine production show that E protein / TLR2 binding leads to the activation of NF-{kappa}B transcription factor that control the expression of multiple pro-inflammatory cytokines including CXCL8. Overall, our findings suggest considering the envelope protein E as a novel target for COVID-19 interventions.

immunology↗

bioRxiv2021

Pseudomonas aeruginosa infection reveals a Caspase-1-dependent neutrophil pyroptosis pathway that restrains damaging Histone release

Multiple neutrophil death programs contribute to host defense against infections. Although expressing all necessary components, neutrophils specifically fail to undergo pyroptosis, a lytic form of cell death triggered by the activation of the pro-inflammatory complex inflammasome. In the light of the arm race, we hypothesized that intrinsic neutrophil pyroptosis resistance might be bypassed in response to specific microbial species. We show that Pseudomonas aeruginosa (P. aeruginosa) stimulates Caspase-1-dependent pyroptosis in human and murine neutrophils. Mechanistically, activated NLRC4 inflammasome supports Caspase-1-driven Gasdermin-D (GSDMD) activation, IL-1{beta} cytokine release and neutrophil pyroptosis. Furthermore, GSDMD activates Peptidyl Arginine Deaminase-4 which drives an "incomplete NETosis" where neutrophil DNA fills the cell cytosol but fails crossing plasma membrane. Finally, we show that neutrophil Caspase-1 account for IL-1{beta} production and contributes to various P. aeruginosa strains spread in mice. Overall, we demonstrate that neutrophils are fully competent for Caspase-1-dependent pyroptosis, which drives an unsuspected "incomplete NETosis". SummaryNeutrophils play an essential roles against infections. Although multiple neutrophil death programs contribute to host defense against infections, they fail to undergo pyroptosis, a pro-inflammatory form of cell death. Upon Infections, pyroptosis can be induced in macrophages or epithelial cells upon activation of pro-inflammatory complexes, inflammasomes that trigger Caspase-1-driven Gasdermin dependent plasma membrane lysis. In the light of host-microbe interactions, we hypothesized that yet to find microbial species might hold the capacity to overcome neutrophil resistance to inflammasome-driven pyroptosis. Among several bacterial species, we describe that the bacterium Pseudomonas aeruginosa specifically engages the NLRC4 inflammasome, which promotes Caspase-1-dependent Gasdermin-D activation and subsequent neutrophil pyroptosis. Furthermore, inflammasome-driven pyroptosis leads to DNA decondensation and expansion into the host cell cytosol but not to the so called Neutrophil Extracellular Trap (NET) release as DNA fails breaching the plasma membrane. Finally, in vivo P. aeruginosa infections highlight that Caspase-1-driven neutrophil pyroptosis is functional and is detrimental upon P. aeruginosa infection. Altogether, our results unexpectedly underline neutrophil competence for Caspase-1-dependent pyroptosis, a process that contributes to host susceptibility to P. aeruginosa infection.

immunology↗

bioRxiv2021

Outer membrane vesicles produced by pathogenic strains of Escherichia coli block autophagic flux and exacerbate inflammasome activation

Escherichia coli strains are responsible for a majority of human extra-intestinal infections, resulting in huge direct medical and social costs. We had previously shown that HlyF encoded by a large virulence plasmid harbored by pathogenic E. coli is not a hemolysin but a cytoplasmic enzyme leading to the overproduction of outer membrane vesicles (OMVs). Here, we show that these specific OMVs inhibit the autophagic flux by impairing the autophagosome - lysosome fusion, thus preventing the formation of acidic autophagolysosome and autophagosome clearance. Furthermore, HlyF-associated OMVs are more prone to activate the non-canonical inflammasome pathway. Since autophagy and inflammation are crucial in the hosts response to infection especially during sepsis, our findings reveal an unsuspected role of OMVs in the crosstalk between bacteria and their host, highlighting the fact that these extracellular vesicles have exacerbated pathogenic properties.

microbiology↗

bioRxiv2021

Phospholipid peroxidation fuels ExoU phospholipase-dependent cell necrosis and supports Pseudomonas aeruginosa-driven pathology

Regulated cell necrosis supports immune and anti-infectious strategies of the body; however, dysregulation of these processes drives pathological organ damage. Pseudomonas aeruginosa expresses a phospholipase, ExoU that triggers pathological host cell necrosis through a poorly characterized pathway. Here, we investigated the molecular and cellular mechanisms of ExoU-mediated necrosis. We show that cellular peroxidised phospholipids enhance ExoU phospholipase activity, which drives necrosis of immune and non-immune cells. Conversely, both the endogenous lipid peroxidation regulator GPX4 and the pharmacological inhibition of lipid peroxidation delay ExoU-dependent cell necrosis and improve bacterial elimination in vitro and in vivo. Our findings also pertain to the ExoU-related phospholipase from the bacterial pathogen Burkholderia thailandensis, suggesting that exploitation of peroxidised phospholipids might be a conserved virulence mechanism among various microbial phospholipases. Overall, our results identify an original lipid peroxidation-based virulence mechanism as a strong contributor of microbial phospholipase-driven pathology.

immunology↗

bioRxiv2020

SARS-CoV-2 replication triggers an MDA-5-dependent interferon production which is unable to efficiently control replication

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the third highly pathogenic coronavirus to spill over to humans in less than 20 years, after SARS-CoV-1 in 2002-2003 and Middle East respiratory syndrome (MERS)-CoV in 2012. SARS-CoV-2 is the etiologic agent of coronavirus disease 19 (COVID-19), which ranges from mild respiratory symptoms to severe lung injury and death in the most severe cases. The COVID-19 pandemic is currently a major health issue worldwide. Immune dysregulation characterized by altered innate cytokine responses is thought to contribute to the pathology of COVID-19 patients, which is a testimony of the fundamental role of the innate immune response against SARS-CoV-2. Here, we further characterized the host cell antiviral response against SARS-CoV-2 by using primary human airway epithelia and immortalized model cell lines. We mainly focused on the type I and III interferon (IFN) responses, which lead to the establishment of an antiviral state through the expression of IFN-stimulated genes (ISGs). Our results demonstrate that both primary airway epithelial cells and model cell lines elicit a robust immune response characterized by a strong induction of type I and III IFN through the detection of viral pathogen molecular patterns (PAMPs) by melanoma differentiation associated gene (MDA)-5. However, despite the high levels of type I and III IFNs produced in response to SARS-CoV-2 infection, the IFN response was unable to control viral replication, whereas IFN pre-treatment strongly inhibited viral replication and de novo production of infectious virions. Taken together, these results highlight the complex and ambiguous interplay between viral replication and the timing of IFN responses.

microbiology↗

bioRxiv2020

Irgm2 and Gate-16 cooperatively dampen targeting of caspase-11 to Gram-negative bacterial products

Inflammatory caspase-11 (rodent) and caspases-4 and -5 (human) detect gram-negative bacterial component LPS in the host cell cytosol, which promotes activation of the non-canonical inflammasome. Although non-canonical inflammasome-induced pyroptosis and IL-1 related cytokine release is of importance to mount an efficient immune response against various bacteria, its unrestrained activation drives sepsis. This suggests that cellular components might tightly control the threshold level of the non-canonical inflammasome in order to ensure efficient but not deleterious inflammatory response. Here we show that the IFN-inducible protein Irgm2 and the ATG8 family member Gate-16 cooperatively slow down non-canonical inflammasome activation both in macrophages and in vivo. Specifically, the Irgm2/Gate-16 axis dampens caspase-11 targeting to intracellular bacteria, which lower caspase-11-mediated pyroptosis and cytokine release. Specifically, deficiency in Irgm2 or Gate16 opens an alternative road for caspase-11 targeting to intracellular bacteria, independently of the classical pathway driven by the Guanylate Binding Proteins (GBPs). Thus, our findings provide new molecular effectors involved at fine-tuning the optimal non-canonical inflammasome response and add novel insights in the understanding of the immune pathways they control.

immunology↗

bioRxiv2019

Type-3 Secretion System-induced pyroptosis protects Pseudomonas against cell-autonomous immunity

Inflammasome-induced pyroptosis comprises a key cell-autonomous immune process against intracellular bacteria, namely the generation of dying cell structures. These so-called pore-induced intracellular traps (PITs) entrap and weaken intracellular microbes. However, the immune importance of pyroptosis against extracellular pathogens remains unclear. Here, we report that Type-3 secretion system (T3SS)-expressing Pseudomonas aeruginosa (P. aeruginosa) escaped PIT immunity by inducing a NLRC4 inflammasome-dependent macrophage pyroptosis response in the extracellular environment. To the contrary, phagocytosis of Salmonella Typhimurium promoted NLRC4-dependent PIT formation and the subsequent bacterial caging. Remarkably, T3SS-deficient Pseudomonas were efficiently sequestered within PIT-dependent caging, which favored exposure to neutrophils. Conversely, both NLRC4 and caspase-11 deficient mice presented increased susceptibility to T3SS-deficient P. aeruginosa challenge, but not to T3SS-expressing P. aeruginosa. Overall, our results uncovered that P. aeruginosa uses its T3SS to overcome inflammasome-triggered pyroptosis, which is primarily effective against intracellular invaders.\n\nImportanceAlthough innate immune components confer host protection against infections, the opportunistic bacterial pathogen Pseudomonas aeruginosa (P. aeruginosa) exploits the inflammatory reaction to thrive. Specifically the NLRC4 inflammasome, a crucial immune complex, triggers an Interleukin (IL)-1{beta} and -18 deleterious host response to P. aeruginosa. Here, we provide evidence that, in addition to IL-1 cytokines, P. aeruginosa also exploits the NLRC4 inflammasome-induced pro-inflammatory cell death, namely pyroptosis, to avoid efficient uptake and killing by macrophages. Therefore, our study reveals that pyroptosis-driven immune effectiveness mainly depends on P. aeruginosa localization. This paves the way toward our comprehension of the mechanistic requirements for pyroptosis effectiveness upon microbial infections and may initiate targeted approaches in order to ameliorate the innate immune functions to infections.\n\nGraphical abstractMacrophages infected with T3SS-expressing P. aeruginosa die in a NLRC4-dependent manner, which allows bacterial escape from PIT-mediated cell-autonomous immunity and neutrophil efferocytosis. However, T3SS-deficient P. aeruginosa is detected by both NLRC4 and caspase-11 inflammasomes, which promotes bacterial trapping and subsequent efferocytosis of P. aeruginosa-containing-PITs by neutrophils.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=64 SRC=\"FIGDIR/small/650333v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (15K):\norg.highwire.dtl.DTLVardef@17e05c4org.highwire.dtl.DTLVardef@aca55forg.highwire.dtl.DTLVardef@9d2853org.highwire.dtl.DTLVardef@1c275f9_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗