scholarly journals Bacterial T6SS Effector EvpP Inhibits Neutrophil Recruitment via Jnk-Caspy Inflammasome Signaling In vivo

2018 ◽  
Author(s):  
Jinchao Tan ◽  
Dahai Yang ◽  
Zhuang Wang ◽  
Xin Zheng ◽  
Yuanxing Zhang ◽  
...  
Keyword(s):  
Bacterial Colonization ◽  
Critical Role ◽  
Neutrophil Recruitment ◽  
Host Cells ◽  
Infection Model ◽  
Inflammasome Activation ◽  
Type Vi Secretion System ◽  
Zebrafish Larvae

ABSTRACTThe type VI secretion system (T6SS) comprises dynamic complex bacterial contractile nanomachines and is used by many bacteria to inhibit or kill other prokaryotic or eukaryotic cells. Previous studies have revealed that T6SS is constitutively active in response to various stimuli, or fires effectors into host cells during infection. It has been proposed that the T6SS effector EvpP in Edwardsiella piscicida can inhibit NLRP3 inflammasome activation via the Ca2+-dependent JNK pathways. Here, we developed an in vivo infection model by microinjecting bacteria into the tail vein muscle of 3-day-post-fertilized zebrafish larvae, and found that both macrophages and neutrophils are essential for bacterial clearance. Further study revealed that EvpP plays a critical role in promoting the pathogenesis of E. piscicida via inhibiting the phosphorylation of Jnk signaling to reduce the expression of cxcl8a, mmp13 and IL-1β in vivo. Subsequently, by utilizing Tg (mpo:eGFP+/+) zebrafish larvae for E. piscicida infection, we found that the EvpP-inhibited Jnk-caspy inflammasome signaling axis significantly suppressed the recruitment of neutrophils to infection sites, and the caspy‐ or IL-1β-MO knockdown larvae were more susceptible to infection and failed to restrict bacterial colonization in vivo.IMPORTANCEInnate immunity is regulated by phagocytic cells and is critical for host control of bacterial infection. In many bacteria, T6SSs can affect bacterial virulence in certain environments, but little is known about the mechanisms underlying T6SS regulation of innate immune responses during infection in vivo. Here, we investigated the role of an E. piscicida T6SS effector EvpP in manipulating the reaction of neutrophils in vivo. We show that EvpP inhibits the activation of Jnk-caspy inflammasome pathway in zebrafish larvae, and reveal that macrophages are essential for neutrophil recruitment in vivo. This interaction improves our understanding about the complex and contextual role of a bacterial T6SS effector in modulating the action of myeloid cells during infection, and offers new insights into the warfare between bacterial weapons and host immunological surveillance.

scholarly journals A critical role of the T3SS effector EseJ in intracellular trafficking and replication ofEdwardsiella piscicidain non-phagocytic cells

2018 ◽  
Author(s):  
Lingzhi Zhang ◽  
Jiatiao Jiang ◽  
Tianjian Hu ◽  
Jin Zhang ◽  
Xiaohong Liu ◽  
...  
Keyword(s):  
Bacterial Colonization ◽  
Critical Role ◽  
Host Cells ◽  
Intracellular Replication ◽  
Phagocytic Cells ◽  
T3ss Effector ◽  
Early Endosomes ◽  
Underlying Mechanisms ◽  
Endosome Maturation

AbstractEdwardsiella piscicida(E. piscicida) is an intracellular pathogen within a broad spectrum of hosts. Essential toE. piscicidavirulence is its ability to survive and replicate inside host cells, yet the underlying mechanisms and the nature of the replicative compartment remain unclear. Here, we characterized its intracellular lifestyle in non-phagocytic cells and showed that intracellular replication ofE. piscicidain non-phagocytic cells is dependent on its type III secretion system. Following internalization,E. piscicidais contained in vacuoles that transiently mature into early endosomes, but subsequently bypasses the classical endosome pathway and fusion with lysosomes which depends on its T3SS. Following a rapid escape from the degradative pathway,E. piscicidawas found to create a specialized replication-permissive niche characterized by endoplasmic reticulum (ER) markers. We also found that a T3SS effector EseJ is responsible for intracellular replication ofE. piscicidaby preventing endosome/lysosome fusion. Furthermore,in vivoexperiments confirmed that EseJ is necessary for bacterial colonization ofE. piscicidain both mice and zebrafish. Thus, this work elucidates the strategies used byE. piscicidato survive and proliferate within host non-phagocytic cells.Author summaryE. piscicidais a facultative intracellular bacterium associated with septicemia and fatal infections in many animals, including fish and humans. However, little is known about its intracellular life, which is important for successful invasion of the host. The present study is the first comprehensive characterization ofE. piscicida’s intracellular life-style in host cells. Upon internalization,E. piscicidais transiently contained in Rab5-positive vacuoles, but the pathogen prevents further endosome maturation and fusion with lysosomes by utilizing an T3SS effector EseJ. In addition, the bacterium creates an specialized replication niche for rapid growth via an interaction with the ER. Our study provides new insights into the strategies used byE. piscicidato successfully establishes an intracellular lifestyle that contributes to its survival and dissemination during infection.

scholarly journals Genetic functions of the NAIP family of inflammasome receptors for bacterial ligands in mice

2016 ◽  
Vol 213 (5) ◽  
pp. 647-656 ◽  
Author(s):  
Yue Zhao ◽  
Jianjin Shi ◽  
Xuyan Shi ◽  
Yupeng Wang ◽  
Fengchao Wang ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Type Iii Secretion ◽  
Physiological Function ◽  
Shigella Flexneri ◽  
Critical Role ◽  
Bacterial Virulence ◽  
Infection Model ◽  
Inflammasome Activation ◽  
Inflammatory Damage

Biochemical studies suggest that the NAIP family of NLR proteins are cytosolic innate receptors that directly recognize bacterial ligands and trigger NLRC4 inflammasome activation. In this study, we generated Naip5−/−, Naip1−/−, and Naip2−/− mice and showed that bone marrow macrophages derived from these knockout mice are specifically deficient in detecting bacterial flagellin, the type III secretion system needle, and the rod protein, respectively. Naip1−/−, Naip2−/−, and Naip5−/− mice also resist lethal inflammasome activation by the corresponding ligand. Furthermore, infections performed in the Naip-deficient macrophages have helped to define the major signal in Legionella pneumophila, Salmonella Typhimurium and Shigella flexneri that is detected by the NAIP/NLRC4 inflammasome. Using an engineered S. Typhimurium infection model, we demonstrate the critical role of NAIPs in clearing bacterial infection and protecting mice from bacterial virulence–induced lethality. These results provide definitive genetic evidence for the important physiological function of NAIPs in antibacterial defense and inflammatory damage–induced lethality in mice.

scholarly journals Edwardsiella piscicida interferes with classical endocytic trafficking and replicates in a specialized replication-permissive niche in non-phagocytic cells

2021 ◽  
Author(s):  
Lingzhi Zhang ◽  
Jiatiao Jiang ◽  
Jin Zhang ◽  
Xiaohong Liu ◽  
Dahai Yang ◽  
...  
Keyword(s):  
Bacterial Colonization ◽  
Secretion System ◽  
Host Cells ◽  
Intracellular Replication ◽  
Type Vi Secretion System ◽  
Phagocytic Cells ◽  
T3ss Effector ◽  
Early Endosomes ◽  
Edwardsiella Piscicida

Edwardsiella piscicida ( E. piscicida ) is an intracellular pathogen within a broad spectrum of hosts. Essential to E. piscicida virulence is its ability to invade and replicate inside host cells, yet the survival mechanisms and the nature of the replicative compartment remain unknown. Here, we characterized its intracellular lifestyle in non-phagocytic cells and showed that intracellular replication of E. piscicida in non-phagocytic cells is dependent on its type III secretion system but not type VI secretion system. Following internalization, E. piscicida is contained in vacuoles that transiently mature into early endosomes but subsequently bypasses the classical endosome pathway and fusion with lysosomes which depend on its T3SS. Following a rapid escape from the degradative pathway, E. piscicida was found to create a specialized replication-permissive niche characterized by endoplasmic reticulum (ER) markers. Furthermore, we found that a T3SS effector EseJ is responsible for intracellular replication of E. piscicida by preventing endosome/lysosome fusion. In vivo experiments also confirmed that EseJ is necessary for bacterial colonization of E. piscicida in the epithelial layer followed by systemic dissemination both in zebrafish and mice. Thus, this work elucidates the tactics used by E. piscicida to survive and proliferate within host non-phagocytic cells. IMPORTANCE E. piscicida is a facultative intracellular bacterium associated with septicemia and fatal infections in many animals, including fish and humans. However, little is known about its intracellular life, which is important for successful invasion of the host. The present study is the first comprehensive characterization of E. piscicida ’s intracellular life-style in host cells. Upon internalization, E. piscicida is transiently contained in Rab5-positive vacuoles, but the pathogen prevents further endosome maturation and fusion with lysosomes by utilizing a T3SS effector EseJ. In addition, the bacterium creates a specialized replication niche for rapid growth via an interaction with the ER. Our study provides new insights into the strategies used by E. piscicida to successfully establishes an intracellular lifestyle that contributes to its survival and dissemination during infection.

scholarly journals The role of Leishmania GP63 in the modulation of innate inflammatory response to Leishmania major infection

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0262158
Author(s):  
Aretha Chan ◽  
Jose-Mauricio Ayala ◽  
Fernando Alvarez ◽  
Ciriaco Piccirillo ◽  
George Dong ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Leishmania Major ◽  
Critical Role ◽  
Protozoan Parasite ◽  
Inflammatory Cells ◽  
Host Cells ◽  
Cell Infection ◽  
Zinc Metalloprotease

Leishmaniasis is a disease caused by the protozoan parasite Leishmania and is known to affect millions of individuals worldwide. In recent years, we have established the critical role played by Leishmania zinc-metalloprotease GP63 in the modulation of host macrophage signalling and functions, favouring its survival and progression within its host. Leishmania major lacking GP63 was reported to cause limited infection in mice, however, it is still unclear how GP63 may influence the innate inflammatory response and parasite survival in an in vivo context. Therefore, we were interested in analyzing the early innate inflammatory events upon Leishmania inoculation within mice and establish whether Leishmania GP63 influences this initial inflammatory response. Experimentally, L. major WT (L. majorWT), L. major GP63 knockout (L. majorKO), or L. major GP63 rescue (L. majorR) were intraperitoneally inoculated in mice and the inflammatory cells recruited were characterized microscopically and by flow cytometry (number and cell type), and their infection determined. Pro-inflammatory markers such as cytokines, chemokines, and extracellular vesicles (EVs, e.g. exosomes) were monitored and proteomic analysis was performed on exosome contents. Data obtained from this study suggest that Leishmania GP63 does not significantly influence the pathogen-induced inflammatory cell recruitment, but rather their activation status and effector function. Concordantly, internalization of promastigotes during early infection could be influenced by GP63 as fewer L. majorKO amastigotes were found within host cells and appear to maintain in host cells over time. Collectively this study provides a clear analysis of innate inflammatory events occurring during L. major infection and further establish the prominent role of the virulence factor GP63 to provide favourable conditions for host cell infection.

scholarly journals Critical role for bone marrow stromal antigen 2 in acute Chikungunya virus infection

2014 ◽  
Vol 95 (11) ◽  
pp. 2450-2461 ◽  
Author(s):  
Wadie D. Mahauad-Fernandez ◽  
Philip H. Jones ◽  
Chioma M. Okeoma
Keyword(s):  
Bone Marrow ◽  
Chikungunya Virus ◽  
Critical Role ◽  
Cd40 Ligand ◽  
Host Cells ◽  
Lymphoid Tissues ◽  
Chikv Infection ◽  
Retroviral Infection

Bone marrow stromal antigen 2 (BST-2; also known as tetherin or CD317) is an IFN-inducible gene that functions to block the release of a range of nascent enveloped virions from infected host cells. However, the role of BST-2 in viral pathogenesis remains poorly understood. BST-2 plays a multifaceted role in innate immunity, as it hinders retroviral infection and possibly promotes infection with some rhabdo- and orthomyxoviruses. This paradoxical role has probably hindered exploration of BST-2 antiviral function in vivo. We reported previously that BST-2 tethers Chikungunya virus (CHIKV)-like particles on the cell plasma membrane. To explore the role of BST-2 in CHIKV replication and host protection, we utilized CHIKV strain 181/25 to examine early events during CHIKV infection in a BST-2−/− mouse model. We observed an interesting dichotomy between WT and BST-2−/− mice. BST-2 deficiency increased inoculation site viral load, culminating in higher systemic viraemia and increased lymphoid tissues tropism. A suppressed inflammatory innate response demonstrated by impaired expression of IFN-α, IFN-γ and CD40 ligand was observed in BST-2−/− mice compared with the WT controls. These findings suggested that, in part, BST-2 protects lymphoid tissues from CHIKV infection and regulates CHIKV-induced inflammatory response by the host.

scholarly journals Peptidyl-Prolyl Isomerase ppiB Is Essential for Proteome Homeostasis and Virulence in Burkholderia pseudomallei

2019 ◽  
Vol 87 (10) ◽  
Author(s):  
Nicole M. Bzdyl ◽  
Nichollas E. Scott ◽  
Isobel H. Norville ◽  
Andrew E. Scott ◽  
Timothy Atkins ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Antimicrobial Treatment ◽  
Infection Model ◽  
Virulence Determinants ◽  
Type Vi Secretion System ◽  
Content Type ◽  
Cyclophilin B ◽  
Novel Treatments

ABSTRACT Burkholderia pseudomallei is the causative agent of melioidosis, a disease endemic to Southeast Asia and northern Australia. Mortality rates in these areas are high even with antimicrobial treatment, and there are few options for effective therapy. Therefore, there is a need to identify antibacterial targets for the development of novel treatments. Cyclophilins are a family of highly conserved enzymes important in multiple cellular processes. Cyclophilins catalyze the cis-trans isomerization of xaa-proline bonds, a rate-limiting step in protein folding which has been shown to be important for bacterial virulence. B. pseudomallei carries a putative cyclophilin B gene, ppiB, the role of which was investigated. A B. pseudomallei ΔppiB (BpsΔppiB) mutant strain demonstrates impaired biofilm formation and reduced motility. Macrophage invasion and survival assays showed that although the BpsΔppiB strain retained the ability to infect macrophages, it had reduced survival and lacked the ability to spread cell to cell, indicating ppiB is essential for B. pseudomallei virulence. This is reflected in the BALB/c mouse infection model, demonstrating the requirement of ppiB for in vivo disease dissemination and progression. Proteomic analysis demonstrates that the loss of PpiB leads to pleiotropic effects, supporting the role of PpiB in maintaining proteome homeostasis. The loss of PpiB leads to decreased abundance of multiple virulence determinants, including flagellar machinery and alterations in type VI secretion system proteins. In addition, the loss of ppiB leads to increased sensitivity toward multiple antibiotics, including meropenem and doxycycline, highlighting ppiB inhibition as a promising antivirulence target to both treat B. pseudomallei infections and increase antibiotic efficacy.

scholarly journals Type VI secretion system and its effectors PdpC, PdpD and OpiA contribute to Francisella virulence in Galleria mellonella larvae

2021 ◽  
Author(s):  
Maj Brodmann ◽  
Sophie Schnider ◽  
Marek Basler
Keyword(s):  
Galleria Mellonella ◽  
Response Regulator ◽  
Infection Model ◽  
Type Vi Secretion System ◽  
Infectious Dose ◽  
Infection Models

Francisella tularensis causes the deadly zoonotic disease tularemia in humans and is able to infect a broad range of organisms including arthropods, which are thought to play a major role in Francisella transmission. However, while mammalian in vitro and in vivo infection models are widely used to investigate Francisella pathogenicity, a detailed characterization of the major Francisella virulence factor, a non-canonical T6SS, in an arthropod in vivo infection model is missing. Here we use Galleria mellonella larvae to analyze the role of the Francisella T6SS and its corresponding effectors in F. novicida virulence. We report that G. mellonella larvae killing depends on the functional T6SS and infectious dose. In contrast to other mammalian in vivo infection models, even one of PdpC, PdpD or OpiA T6SS effectors is sufficient to kill G. mellonella larvae while sheath recycling by ClpB is dispensable. We further demonstrate that treatment by polyethylene glycol (PEG) activates Francisella T6SS in liquid culture and that this is independent of the response regulator PmrA. PEG-activated IglC secretion is dependent on T6SS structural component PdpB but independent of putative effectors PdpC, PdpD, AnmK and OpiB1-3. The results of larvae infection and secretion assay suggest that AnmK, a putative T6SS component with unknown function, interferes with OpiA-mediated toxicity but not with general T6SS activity. We establish that the easy-to-use G. mellonella larvae infection model provides new insights into function of T6SS and pathogenesis of Francisella.

scholarly journals An infection-induced RhoB-Beclin 1-Hsp90 complex enhances clearance of uropathogenic Escherichia coli

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chunhui Miao ◽  
Mingyu Yu ◽  
Geng Pei ◽  
Zhenyi Ma ◽  
Lisong Zhang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Treatment Strategies ◽  
Uropathogenic Escherichia Coli ◽  
Beclin 1 ◽  
Host Cells ◽  
Infection Model ◽  
Intracellular Bacteria ◽  
Bladder Epithelium ◽  
Binding Residue

AbstractHost cells use several anti-bacterial pathways to defend against pathogens. Here, using a uropathogenic Escherichia coli (UPEC) infection model, we demonstrate that bacterial infection upregulates RhoB, which subsequently promotes intracellular bacteria clearance by inducing LC3 lipidation and autophagosome formation. RhoB binds with Beclin 1 through its residues at 118 to 140 and the Beclin 1 CCD domain, with RhoB Arg133 being the key binding residue. Binding of RhoB to Beclin 1 enhances the Hsp90-Beclin 1 interaction, preventing Beclin 1 degradation. RhoB also directly interacts with Hsp90, maintaining RhoB levels. UPEC infections increase RhoB, Beclin 1 and LC3 levels in bladder epithelium in vivo, whereas Beclin 1 and LC3 levels as well as UPEC clearance are substantially reduced in RhoB+/− and RhoB−/− mice upon infection. We conclude that when stimulated by UPEC infections, host cells promote UPEC clearance through the RhoB-Beclin 1-HSP90 complex, indicating RhoB may be a useful target when developing UPEC treatment strategies.

scholarly journals The role of the PZP domain of AF10 in acute leukemia driven by AF10 translocations

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Brianna J. Klein ◽  
Anagha Deshpande ◽  
Khan L. Cox ◽  
Fan Xuan ◽  
Mohamad Zandian ◽  
...  
Keyword(s):  
Critical Role ◽  
Cellular Transformation ◽  
Acute Leukemias ◽  
Hematopoietic Stem ◽  
Nucleosome Core ◽  
Stem And Progenitor Cells ◽  
Transforming Activity

AbstractChromosomal translocations of the AF10 (or MLLT10) gene are frequently found in acute leukemias. Here, we show that the PZP domain of AF10 (AF10PZP), which is consistently impaired or deleted in leukemogenic AF10 translocations, plays a critical role in blocking malignant transformation. Incorporation of functional AF10PZP into the leukemogenic CALM-AF10 fusion prevents the transforming activity of the fusion in bone marrow-derived hematopoietic stem and progenitor cells in vitro and in vivo and abrogates CALM-AF10-mediated leukemogenesis in vivo. Crystallographic, biochemical and mutagenesis studies reveal that AF10PZP binds to the nucleosome core particle through multivalent contacts with the histone H3 tail and DNA and associates with chromatin in cells, colocalizing with active methylation marks and discriminating against the repressive H3K27me3 mark. AF10PZP promotes nuclear localization of CALM-AF10 and is required for association with chromatin. Our data indicate that the disruption of AF10PZP function in the CALM-AF10 fusion directly leads to transformation, whereas the inclusion of AF10PZP downregulates Hoxa genes and reverses cellular transformation. Our findings highlight the molecular mechanism by which AF10 targets chromatin and suggest a model for the AF10PZP-dependent CALM-AF10-mediated leukemogenesis.

Sign in / Sign up

Export Citation Format

Share Document