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Patterson LL, Byerly CD, Solomon R, Pittner N, Bui DC, Patel J, McBride JW. Ehrlichia Notch signaling induction promotes XIAP stability and inhibits apoptosis. Infect Immun 2023; 91:e0000223. [PMID: 37594275 PMCID: PMC10501217 DOI: 10.1128/iai.00002-23] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 06/07/2023] [Indexed: 08/19/2023] Open
Abstract
Ehrlichia chaffeensis has evolved multiple strategies to evade innate defenses of the mononuclear phagocyte. Recently, we reported the E. chaffeensis tandem repeat protein (TRP)120 effector functions as a Notch ligand mimetic and a ubiquitin ligase that degrades the nuclear tumor suppressor, F-box and WD repeat domain-containing 7, a negative regulator of Notch. The Notch intracellular domain (NICD) is known to inhibit apoptosis primarily by interacting with X-linked inhibitor of apoptosis protein (XIAP) to prevent degradation. In this study, we determined that E. chaffeensis activation of Notch signaling increases XIAP levels, thereby inhibiting apoptosis through both the intrinsic and executioner pathways. Increased NICD and XIAP levels were detected during E. chaffeensis infection and after TRP120 Notch ligand mimetic peptide treatment. Conversely, XIAP levels were reduced in the presence of Notch inhibitor DAPT. Cytoplasmic and nuclear colocalization of NICD and XIAP was observed during infection and a direct interaction was confirmed by co-immunoprecipitation. Procaspase levels increased temporally during infection, consistent with increased XIAP levels; however, knockdown (KD) of XIAP during infection significantly increased apoptosis and Caspase-3, -7, and -9 levels. Furthermore, treatment with SM-164, a second mitochondrial activator of caspases (Smac/DIABLO) antagonist, resulted in decreased procaspase levels and increased caspase activation, induced apoptosis, and significantly decreased infection. In addition, RNAi KD of XIAP also decreased infection and significantly increased apoptosis. Moreover, ectopic expression of TRP120 HECT Ub ligase catalytically defective mutant in HeLa cells decreased NICD and XIAP levels and increased caspase activation compared to HeLa cells with functional HECT Ub ligase catalytic activity (TRP120-WT). This investigation reveals a mechanism whereby E. chaffeensis modulates Notch signaling to stabilize XIAP and inhibit apoptosis.
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Affiliation(s)
- LaNisha L. Patterson
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Caitlan D. Byerly
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Regina Solomon
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Nicholas Pittner
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Duc Cuong Bui
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jignesh Patel
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, USA
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, Texas, USA
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA
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Patterson LL, Byerly CD, Solomon R, Pittner N, Bui DC, Patel J, McBride JW. Ehrlichia Notch signaling induction promotes XIAP stability and inhibits apoptosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.06.523066. [PMID: 36711597 PMCID: PMC9881962 DOI: 10.1101/2023.01.06.523066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Ehrlichia chaffeensis has evolved multiple strategies to evade innate defenses of the mononuclear phagocyte. Recently, we reported the E. chaffeensis TRP120 effector functions as a Notch ligand mimetic and a ubiquitin ligase that degrades the nuclear tumor suppressor, F-box and WD repeat domain-containing 7 (FBW7), a negative regulator of Notch. The Notch receptor intracellular domain (NICD) is known to inhibit apoptosis primarily by interacting with X-linked inhibitor of apoptosis protein (XIAP) to prevent degradation. In this study, we determined E. chaffeensis activation of Notch signaling increases XIAP levels, thereby inhibiting intrinsic apoptosis. Increased NICD and XIAP levels were detected during E. chaffeensis infection and after TRP120 Notch ligand mimetic peptide treatment. Conversely, XIAP levels were reduced in the presence of Notch inhibitor DAPT. Cytoplasmic colocalization of NICD and XIAP was observed during infection and a direct interaction was confirmed by co-immunoprecipitation. Procaspase levels increased temporally during infection, consistent with increased XIAP levels; however, knockdown of XIAP during infection significantly increased apoptosis and Caspase-3, -7 and -9 levels. Further, treatment with SM-164, a second mitochondrial activator of caspases (Smac/DIABLO) antagonist, resulted in decreased procaspase levels and increased caspase activation, induced apoptosis, and significantly decreased infection. In addition, iRNA knockdown of XIAP also decreased infection and significantly increased apoptosis. Moreover, ectopic expression of TRP120 HECT Ub ligase catalytically defective mutant in HeLa cells decreased NICD and XIAP levels and increased caspase activation compared to WT. This investigation reveals a mechanism whereby E. chaffeensis repurposes Notch signaling to stabilize XIAP and inhibit apoptosis. Author Summary Ehrlichia chaffeensis is a tick-borne, obligately intracellular bacterium that exhibits tropism for mononuclear phagocytes. E. chaffeensis survives by mobilizing various molecular strategies to promote cell survival, including modulation of apoptosis. This investigation reveals an E. chaffeensis initiated, Notch signaling regulated, antiapoptotic mechanism involving inhibitor of apoptosis proteins (IAPs). Herein, we demonstrate that E. chaffeensis induced Notch activation results in Notch intracellular domain stabilization of X-linked inhibitor of apoptosis protein (XIAP) to inhibit intrinsic apoptosis. This study highlights a novel mechanistic strategy whereby intracellular pathogens repurpose evolutionarily conserved eukaryotic signaling pathways to engage an antiapoptotic program for intracellular survival.
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Sharma P, Vijaykumar A, Raghavan JV, Rananaware SR, Alakesh A, Bodele J, Rehman JU, Shukla S, Wagde V, Nadig S, Chakrabarti S, Visweswariah SS, Nandi D, Gopal B, Jhunjhunwala S. Particle uptake driven phagocytosis in macrophages and neutrophils enhances bacterial clearance. J Control Release 2022; 343:131-141. [PMID: 35085696 PMCID: PMC7615985 DOI: 10.1016/j.jconrel.2022.01.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 12/13/2022]
Abstract
Humans are exposed to numerous synthetic foreign particles in the form of drug delivery systems and diagnostic agents. Specialized immune cells (phagocytes) clear these particles by phagocytosing and attempting to degrade them. The process of recognition and internalization of the particles may trigger changes in the function of phagocytes. Some of these changes, especially the ability of a particle-loaded phagocyte to take up and neutralize pathogens, remains poorly studied. Herein, we demonstrate that the uptake of non-stimulatory cargo-free particles enhances the phagocytic ability of monocytes, macrophages and neutrophils. The enhancement in phagocytic ability was independent of particle properties, such as size or the base material constituting the particle. Additionally, we show that the increased phagocytosis was not a result of cellular activation or cellular heterogeneity but was driven by changes in cell membrane fluidity and cellular compliance. A consequence of the enhanced phagocytic activity was that particulate-laden immune cells neutralize Escherichia coli (E. coli) faster in culture. Moreover, when administered in mice as a prophylactic, particulates enable faster clearance of E. coli and Staphylococcus epidermidis. Together, we demonstrate that the process of uptake induces cellular changes that favor additional phagocytic events. This study provides insights into using non-stimulatory cargo-free particles to engineer immune cell functions for applications involving faster clearance of phagocytosable abiotic and biotic material.
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Affiliation(s)
- Preeti Sharma
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bengaluru 560012, India
| | - Anjali Vijaykumar
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bengaluru 560012, India
| | | | | | - Alakesh Alakesh
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bengaluru 560012, India
| | - Janhavi Bodele
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bengaluru 560012, India
| | - Junaid Ur Rehman
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bengaluru 560012, India
| | - Shivani Shukla
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bengaluru 560012, India
| | - Virta Wagde
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bengaluru 560012, India
| | - Savitha Nadig
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru 560012, India
| | - Sveta Chakrabarti
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru 560012, India
| | - Sandhya S Visweswariah
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru 560012, India
| | - Dipankar Nandi
- Department of Biochemistry, Indian Institute of Science, Bengaluru 560012, India
| | | | - Siddharth Jhunjhunwala
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bengaluru 560012, India.
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Chen CL, Chien SC, Leu TH, Harn HIC, Tang MJ, Hor LI. Vibrio vulnificus MARTX cytotoxin causes inactivation of phagocytosis-related signaling molecules in macrophages. J Biomed Sci 2017; 24:58. [PMID: 28822352 PMCID: PMC5563386 DOI: 10.1186/s12929-017-0368-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 08/13/2017] [Indexed: 01/22/2023] Open
Abstract
Background Vibrio vulnificus is a marine bacterial species that causes opportunistic infections manifested by serious skin lesions and fulminant septicemia in humans. We have previously shown that the multifunctional autoprocessing repeats in toxin (MARTXVv1) of a biotype 1 V. vulnificus strain promotes survival of this organism in the host by preventing it from engulfment by the phagocytes. The purpose of this study was to further explore how MARTXVv1 inhibits phagocytosis of this microorganism by the macrophage. Methods We compared between a wild-type V. vulnificus strain and its MARTXVv1-deficient mutant for a variety of phagocytosis-related responses, including morphological change and activation of signaling molecules, they induced in the macrophage. We also characterized a set of MARTXVv1 domain-deletion mutants to define the regions associated with antiphagocytosis activity. Results The RAW 264.7 cells and mouse peritoneal exudate macrophages underwent cell rounding accompanied by F-actin disorganization in the presence of MARTXVv1. In addition, phosphorylation of some F-actin rearrangement-associated signaling molecules, including Lyn, Fgr and Hck of the Src family kinases (SFKs), focal adhesion kinase (FAK), proline-rich tyrosine kinase 2 (Pyk2), phosphoinositide 3-kinase (PI3K) and Akt, but not p38, was decreased. By using specific inhibitors, we found that these kinases were all involved in the phagocytosis of MARTXVv1-deficient mutant in an order of SFKs-FAK/Pyk2-PI3K-Akt. Deletion of the effector domains in the central region of MARTXVv1 could lead to reduced cytotoxicity, depending on the region and size of deletion, but did not affect the antiphagocytosis activity and ability to cause rounding of macrophage. Reduced phosphorylation of Akt was closely associated with inhibition of phagocytosis by the wild-type strain and MARTXVv1 domain-deletion mutants, and expression of the constitutively active Akt, myr-Akt, enhanced the engulfment of these strains by macrophage. Conclusions MARTXVv1 could inactivate the SFKs-FAK/Pyk2-PI3K-Akt signaling pathway in the macrophages. This might lead to impaired phagocytosis of the V. vulnificus-infected macrophage. The majority of the central region of MARTXVv1 is not associated with the antiphagocytosis activity. Electronic supplementary material The online version of this article (doi:10.1186/s12929-017-0368-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chun-Liang Chen
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Shu-Chun Chien
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Tzeng-Horng Leu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan.,Department of Pharmacology College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Hans I-Chen Harn
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Ming-Jer Tang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan.,Department of Physiology, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Lien-I Hor
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan. .,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan.
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Liebl D, Qi X, Zhe Y, Barnett TC, Teasdale RD. SopB-Mediated Recruitment of SNX18 Facilitates Salmonella Typhimurium Internalization by the Host Cell. Front Cell Infect Microbiol 2017; 7:257. [PMID: 28664153 PMCID: PMC5471308 DOI: 10.3389/fcimb.2017.00257] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 05/31/2017] [Indexed: 11/16/2022] Open
Abstract
To invade epithelial cells, Salmonella enterica serovar Typhimurium (S. Typhimurium) induces macropinocytosis through the action of virulence proteins delivered across the host cell membrane via a type III secretion system. We show that after docking at the plasma membrane S. Typhimurium triggers rapid recruitment of cytosolic SNX18, a SH3-PX-BAR domain sorting nexin protein, to the bacteria-induced membrane ruffles and to the nascent Salmonella-containing vacuole. SNX18 recruitment required the inositol-phosphatase activity of the Salmonella effector SopB and an intact phosphoinositide-binding site within the PX domain of SNX18, but occurred independently of Rho-GTPases Rac1 and Cdc42 activation. SNX18 promotes formation of the SCV from the plasma membrane by acting as a scaffold to recruit Dynamin-2 and N-WASP in a process dependent on the SH3 domain of SNX18. Quantification of bacteria uptake revealed that overexpression of SNX18 increased bacteria internalization, whereas a decrease was detected in cells overexpressing the phosphoinositide-binding mutant R303Q, the ΔSH3 mutant, and in cells where endogenous levels of SNX18 were knocked-down. This study identifies SNX18 as a novel target of SopB and suggests a mechanism where S. Typhimurium engages host factors via local manipulation of phosphoinositide composition at the site of invasion to orchestrate the internalization process.
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Affiliation(s)
- David Liebl
- Institute for Molecular Bioscience, The University of QueenslandBrisbane, QLD, Australia
| | - Xiaying Qi
- Institute for Molecular Bioscience, The University of QueenslandBrisbane, QLD, Australia
| | - Yang Zhe
- Institute for Molecular Bioscience, The University of QueenslandBrisbane, QLD, Australia
| | - Timothy C Barnett
- Australian Infectious Diseases Research Centre, The University of QueenslandBrisbane, QLD, Australia.,School of Chemistry and Molecular Biosciences, The University of QueenslandBrisbane, QLD, Australia
| | - Rohan D Teasdale
- Institute for Molecular Bioscience, The University of QueenslandBrisbane, QLD, Australia.,Australian Infectious Diseases Research Centre, The University of QueenslandBrisbane, QLD, Australia.,School of Biomedical Sciences, The University of QueenslandBrisbane, QLD, Australia
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Bewley MA, Belchamber KBR, Chana KK, Budd RC, Donaldson G, Wedzicha JA, Brightling CE, Kilty I, Donnelly LE, Barnes PJ, Singh D, Whyte MKB, Dockrell DH. Differential Effects of p38, MAPK, PI3K or Rho Kinase Inhibitors on Bacterial Phagocytosis and Efferocytosis by Macrophages in COPD. PLoS One 2016; 11:e0163139. [PMID: 27680884 PMCID: PMC5040258 DOI: 10.1371/journal.pone.0163139] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 09/02/2016] [Indexed: 12/22/2022] Open
Abstract
Pulmonary inflammation and bacterial colonization are central to the pathogenesis of chronic obstructive pulmonary disease (COPD). Defects in macrophage phagocytosis of both bacteria and apoptotic cells contribute to the COPD phenotype. Small molecule inhibitors with anti-inflammatory activity against p38 mitogen activated protein kinases (MAPKs), phosphatidyl-inositol-3 kinase (PI3K) and Rho kinase (ROCK) are being investigated as novel therapeutics in COPD. Concerns exist, however, about off-target effects. We investigated the effect of p38 MAPK inhibitors (VX745 and SCIO469), specific inhibitors of PI3K α (NVS-P13K-2), δ (NVS-P13K-3) or γ (NVS-P13K-5) and a ROCK inhibitor PF4950834 on macrophage phagocytosis, early intracellular killing of bacteria and efferocytosis of apoptotic neutrophils. Alveolar macrophages (AM) obtained from broncho-alveolar lavage (BAL) or monocyte-derived macrophages (MDM) from COPD patients (GOLD stage II/III) enrolled from a well characterized clinical cohort (MRC COPD-MAP consortium) or from healthy ex-smoker controls were studied. Both COPD AM and MDM exhibited lower levels of bacterial phagocytosis (using Streptococcus pneumoniae and non-typeable Haemophilus influenzae) and efferocytosis than healthy controls. None of the inhibitors altered bacterial internalization or early intracellular bacterial killing in AM or MDM. Conversely PF4950834, but not other inhibitors, enhanced efferocytosis in COPD AM and MDM. These results suggest none of these inhibitors are likely to exacerbate phagocytosis-related defects in COPD, while confirming ROCK inhibitors can enhance efferocytosis in COPD.
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Affiliation(s)
- Martin A. Bewley
- Department of Infection, Immunity and Cardiovascular Disease and The Florey Institute for Host-Pathogen Interactions, University of Sheffield Medical School, Sheffield, United Kingdom
- * E-mail:
| | - Kylie B. R. Belchamber
- Airway Disease National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Kirandeep K. Chana
- Airway Disease National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Richard C. Budd
- Department of Infection, Immunity and Cardiovascular Disease and The Florey Institute for Host-Pathogen Interactions, University of Sheffield Medical School, Sheffield, United Kingdom
- Sheffield Teaching Hospitals Foundation Trust, Sheffield, United Kingdom
- Centre for Respiratory Medicine and Allergy, Institute of Inflammation and Repair, Manchester Academic Health Science Centre, The University of Manchester and University Hospital of South Manchester NHS Foundation Trust, Manchester, United Kingdom
| | - Gavin Donaldson
- Airway Disease National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Jadwiga A. Wedzicha
- Airway Disease National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | | | - Iain Kilty
- Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Louise E. Donnelly
- Airway Disease National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Peter J. Barnes
- Airway Disease National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Dave Singh
- Centre for Respiratory Medicine and Allergy, Institute of Inflammation and Repair, Manchester Academic Health Science Centre, The University of Manchester and University Hospital of South Manchester NHS Foundation Trust, Manchester, United Kingdom
| | - Moira K. B. Whyte
- Department of Respiratory Medicine and MRC Centre for Inflammation Research, University of Edinburgh, Edinburgh, United Kingdom
| | - David H. Dockrell
- Department of Infection, Immunity and Cardiovascular Disease and The Florey Institute for Host-Pathogen Interactions, University of Sheffield Medical School, Sheffield, United Kingdom
- Sheffield Teaching Hospitals Foundation Trust, Sheffield, United Kingdom
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Ehrlichia chaffeensis Exploits Canonical and Noncanonical Host Wnt Signaling Pathways To Stimulate Phagocytosis and Promote Intracellular Survival. Infect Immun 2015; 84:686-700. [PMID: 26712203 DOI: 10.1128/iai.01289-15] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 12/11/2015] [Indexed: 11/20/2022] Open
Abstract
Ehrlichia chaffeensis invades and survives in phagocytes by modulating host cell processes and evading innate defenses, but the mechanisms are not fully defined. Recently we have determined that E. chaffeensis tandem repeat proteins (TRPs) are type 1 secreted effectors involved in functionally diverse interactions with host targets, including components of the evolutionarily conserved Wnt signaling pathways. In this study, we demonstrated that induction of host canonical and noncanonical Wnt pathways by E. chaffeensis TRP effectors stimulates phagocytosis and promotes intracellular survival. After E. chaffeensis infection, canonical and noncanonical Wnt signalings were significantly stimulated during early stages of infection (1 to 3 h) which coincided with dephosphorylation and nuclear translocation of β-catenin, a major canonical Wnt signal transducer, and NFATC1, a noncanonical Wnt transcription factor. In total, the expression of ∼44% of Wnt signaling target genes was altered during infection. Knockdown of TRP120-interacting Wnt pathway components/regulators and other critical components, such as Wnt5a ligand, Frizzled 5 receptor, β-catenin, nuclear factor of activated T cells (NFAT), and major signaling molecules, resulted in significant reductions in the ehrlichial load. Moreover, small-molecule inhibitors specific for components of canonical and noncanonical (Ca(2+) and planar cell polarity [PCP]) Wnt pathways, including IWP-2, which blocks Wnt secretion, significantly decreased ehrlichial infection. TRPs directly activated Wnt signaling, as TRP-coated microspheres triggered phagocytosis which was blocked by Wnt pathway inhibitors, demonstrating a key role of TRP activation of Wnt pathways to induce ehrlichial phagocytosis. These novel findings reveal that E. chaffeensis exploits canonical and noncanonical Wnt pathways through TRP effectors to facilitate host cell entry and promote intracellular survival.
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Askar B, Ibrahim H, Barrow P, Foster N. Vasoactive intestinal peptide (VIP) differentially affects inflammatory immune responses in human monocytes infected with viable Salmonella or stimulated with LPS. Peptides 2015. [PMID: 26206287 DOI: 10.1016/j.peptides.2015.06.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We compared the effect of VIP on human blood monocytes infected with Salmonella typhimurium 4/74 or stimulated with LPS. VIP (10(-7)M) increased monocyte viability by 24% and 9% when cultured for 24h with 4/74 or Salmonella LPS (100ng/ml), respectively. Significantly increased (P<0.05) numbers of 4/74 were also recovered from monocytes co-cultured with VIP after 6h post-infection (pi) and this remained high after 24h pi. Both 4/74 and LPS increased (P<0.05) the concentration of TNF-α, IL-1β and IL-6 measured in monocyte supernatants. However, LPS induced this effect more rapidly while, with the exception of IL-6, 4/74 induced higher concentrations (P<0.05). VIP significantly decreased (P<0.05) TNF-α and IL-1β production by 4/74-infected monocytes after 6 pi, but only after 24h in LPS-cultured monocytes. This trend was reversed for IL-6 production. However, TNF-α and IL-1β production by 4/74-infected monocytes, cultured with VIP, still remained higher (P<0.05) than concentrations measured in supernatants cultured only with LPS. VIP also increased (P<0.05) production of anti-inflammatory IL-10 in both 4/74 and LPS cultures after 24h. We also show a differential effect of VIP on the expression of TNFα and IL-6 receptors, since VIP was only able to decreased expression in LPS-stimulated monocytes but not in 4/74-infected monocytes. In conclusion, we show a differential effect of VIP on human monocytes infected with virulent Salmonella or stimulated with LPS. Our study suggests that the use of VIP in bacteraemia and/or sepsis may be limited to an adjunctive therapy to antibiotic treatment.
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Affiliation(s)
- Basim Askar
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, UK
| | - Hiba Ibrahim
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, UK
| | - Paul Barrow
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, UK
| | - Neil Foster
- School of Veterinary Medicine and Science, University of Nottingham, Nottingham, UK.
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9
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Lai XH, Xu Y, Chen XM, Ren Y. Macrophage cell death upon intracellular bacterial infection. ACTA ACUST UNITED AC 2015; 2:e779. [PMID: 26690967 DOI: 10.14800/macrophage.779] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Macrophage-pathogen interaction is a complex process and the outcome of this tag-of-war for both sides is to live or die. Without attempting to be comprehensive, this review will discuss the complexity and significance of the interaction outcomes between macrophages and some facultative intracellular bacterial pathogens as exemplified by Francisella, Salmonella, Shigella and Yersinia. Upon bacterial infection, macrophages can die by a variety of ways, such as apoptosis, autophagic cell death, necrosis, necroptosis, oncosis, pyronecrosis, pyroptosis etc, which is the focus of this review.
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Affiliation(s)
- Xin-He Lai
- Institute of Inflammation and Diseases, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China ; Institute of Translational Medicine, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yunsheng Xu
- Institute of Inflammation and Diseases, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China ; Institute of Translational Medicine, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China ; Department of Dermato-venerology, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xiao-Ming Chen
- Institute of Inflammation and Diseases, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China ; Institute of Translational Medicine, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China ; Department of Pediatric Surgery, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yi Ren
- Institute of Inflammation and Diseases, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China ; Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, USA)
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10
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Nakayama M, Inoue T, Naito M, Nakayama K, Ohara N. Attenuation of the phosphatidylinositol 3-kinase/Akt signaling pathway by Porphyromonas gingivalis gingipains RgpA, RgpB, and Kgp. J Biol Chem 2015; 290:5190-5202. [PMID: 25564612 DOI: 10.1074/jbc.m114.591610] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Porphyromonas gingivalis is a major pathogen of periodontal diseases, including periodontitis. We have investigated the effect of P. gingivalis infection on the PI3K/Akt (protein kinase B) signaling pathway in gingival epithelial cells. Here, we found that live P. gingivalis, but not heat-killed P. gingivalis, reduced Akt phosphorylation at both Thr-308 and Ser-473, which implies a decrease in Akt activity. Actually, PI3K, which is upstream of Akt, was also inactivated by P. gingivalis. Furthermore, glycogen synthase kinase 3α/β, mammalian target of rapamycin, and Bad, which are downstream proteins in the PI3K/Akt cascade, were also dephosphorylated, a phenomenon consistent with Akt inactivation by P. gingivalis. However, these events did not require direct interaction between bacteria and host cells and were independent of P. gingivalis invasion into the cells. The use of gingipain-specific inhibitors and a gingipain-deficient P. gingivalis mutant KDP136 revealed that the gingipains and their protease activities were essential for the inactivation of PI3K and Akt. The associations between the PI3K regulatory subunit p85α and membrane proteins were disrupted by wild-type P. gingivalis. Moreover, PDK1 translocation to the plasma membrane was reduced by wild-type P. gingivalis, but not KDP136, indicating little production of phosphatidylinositol 3,4,5-triphosphate by PI3K. Therefore, it is likely that PI3K failed to transmit homeostatic extracellular stimuli to intracellular signaling pathways by gingipains. Taken together, our findings indicate that P. gingivalis attenuates the PI3K/Akt signaling pathway via the proteolytic effects of gingipains, resulting in the dysregulation of PI3K/Akt-dependent cellular functions and the destruction of epithelial barriers.
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Affiliation(s)
- Masaaki Nakayama
- From the Department of Oral Microbiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and; the Advanced Research Center for Oral and Craniofacial Sciences, Dental School, Okayama University, Okayama 700-8558 and
| | - Tetsuyoshi Inoue
- From the Department of Oral Microbiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and; the Advanced Research Center for Oral and Craniofacial Sciences, Dental School, Okayama University, Okayama 700-8558 and
| | - Mariko Naito
- the Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, 852-8588, Japan
| | - Koji Nakayama
- the Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, 852-8588, Japan
| | - Naoya Ohara
- From the Department of Oral Microbiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and; the Advanced Research Center for Oral and Craniofacial Sciences, Dental School, Okayama University, Okayama 700-8558 and.
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11
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Subramanian K, Winarsih I, Keerthani C, Ho B, Ding JL. Preferential silent survival of intracellular bacteria in hemoglobin-primed macrophages. J Innate Immun 2014; 6:515-29. [PMID: 24685988 DOI: 10.1159/000358236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 12/27/2013] [Indexed: 11/19/2022] Open
Abstract
Hemolysis releases hemoglobin (Hb), a prooxidant, into circulation. While the heme iron is a nutrient for the invading pathogens, it releases ROS, which is both microbicidal and cytotoxic, making it a double-edged sword. Previously, we found a two-pass detoxification mechanism involving the endocytosis of Hb into monocytes in collaboration with vascular endothelial cells to overcome oxidative damage. This prompted us to examine the effect of Hb priming on host cell viability and intracellular bacterial clearance during a hemolytic infection. Here, we demonstrate that Hb-primed macrophages harbor a higher intracellular bacterial load but with suppressed apoptosis. p-ERK and p-p38 MAPK were significantly downregulated, with concomitant impairment of Bax and downstream caspases. The Hb-primed cells harboring intracellular bacteria upregulated anti-inflammatory IL-10 and downregulated proinflammatory TNF-α, which further enhanced the infectivity of the neighboring cells. Our findings suggest that opportunistic intracellular pathogens exploit the Hb-scavenging machinery of the host to silently persist within the circulating phagocytes by suppressing apoptosis while escaping immune surveillance.
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Affiliation(s)
- Karthik Subramanian
- Department of Biological Sciences, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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12
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Dunne KA, Allam A, McIntosh A, Houston SA, Cerovic V, Goodyear CS, Roe AJ, Beatson SA, Milling SW, Walker D, Wall DM. Increased S-nitrosylation and proteasomal degradation of caspase-3 during infection contribute to the persistence of adherent invasive Escherichia coli (AIEC) in immune cells. PLoS One 2013; 8:e68386. [PMID: 23861899 PMCID: PMC3701656 DOI: 10.1371/journal.pone.0068386] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 06/04/2013] [Indexed: 01/12/2023] Open
Abstract
Adherent invasive Escherichia coli (AIEC) have been implicated as a causative agent of Crohn’s disease (CD) due to their isolation from the intestines of CD sufferers and their ability to persist in macrophages inducing granulomas. The rapid intracellular multiplication of AIEC sets it apart from other enteric pathogens such as Salmonella Typhimurium which after limited replication induce programmed cell death (PCD). Understanding the response of infected cells to the increased AIEC bacterial load and associated metabolic stress may offer insights into AIEC pathogenesis and its association with CD. Here we show that AIEC persistence within macrophages and dendritic cells is facilitated by increased proteasomal degradation of caspase-3. In addition S-nitrosylation of pro- and active forms of caspase-3, which can inhibit the enzymes activity, is increased in AIEC infected macrophages. This S-nitrosylated caspase-3 was seen to accumulate upon inhibition of the proteasome indicating an additional role for S-nitrosylation in inducing caspase-3 degradation in a manner independent of ubiquitination. In addition to the autophagic genetic defects that are linked to CD, this delay in apoptosis mediated in AIEC infected cells through increased degradation of caspase-3, may be an essential factor in its prolonged persistence in CD patients.
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Affiliation(s)
- Karl A. Dunne
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Amr Allam
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Anne McIntosh
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Stephanie A. Houston
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Vuk Cerovic
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Carl S. Goodyear
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Andrew J. Roe
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Scott A. Beatson
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, University of Queensland, St. Lucia, Queensland, Australia
| | - Simon W. Milling
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Daniel Walker
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Daniel M. Wall
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
- * E-mail:
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13
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Blomgran R, Patcha Brodin V, Verma D, Bergström I, Söderkvist P, Sjöwall C, Eriksson P, Lerm M, Stendahl O, Särndahl E. Common genetic variations in the NALP3 inflammasome are associated with delayed apoptosis of human neutrophils. PLoS One 2012; 7:e31326. [PMID: 22403613 PMCID: PMC3293864 DOI: 10.1371/journal.pone.0031326] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 01/06/2012] [Indexed: 12/20/2022] Open
Abstract
Background Neutrophils are key-players in the innate host defense and their programmed cell death and removal are essential for efficient resolution of inflammation. These cells recognize a variety of pathogens, and the NOD-like receptors (NLRs) have been suggested as intracellular sensors of microbial components and cell injury/stress. Some NLR will upon activation form multi-protein complexes termed inflammasomes that result in IL-1β production. NLR mutations are associated with auto-inflammatory syndromes, and our previous data propose NLRP3 (Q705K)/CARD-8 (C10X) polymorphisms to contribute to increased risk and severity of inflammatory disease by acting as genetic susceptibility factors. These gene products are components of the NALP3 inflammasome, and approximately 6.5% of the Swedish population are heterozygote carriers of these combined gene variants. Since patients carrying the Q705K/C10X polymorphisms display leukocytosis, the aim of the present study was to find out whether the inflammatory phenotype was related to dysfunctional apoptosis and impaired clearance of neutrophils by macrophages. Methods and Findings Patients carrying the Q705K/C10X polymorphisms displayed significantly delayed spontaneous as well as microbe-induced apoptosis compared to matched controls. Western blotting revealed increased levels and phosphorylation of Akt and Mcl-1 in the patients' neutrophils. In contrast to macrophages from healthy controls, macrophages from the patients produced lower amounts of TNF; suggesting impaired macrophage clearance response. Conclusions The Q705K/C10X polymorphisms are associated with delayed apoptosis of neutrophils. These findings are explained by altered involvement of different regulators of apoptosis, resulting in an anti-apoptotic profile. Moreover, the macrophage response to ingestion of microbe-induced apoptotic neutrophils is altered in the patients. Taken together, the patients display impaired turnover and clearance of apoptotic neutrophils, pointing towards a dysregulated innate immune response that influences the resolution of inflammation. The future challenge is to understand how microbes affect the activation of inflammasomes, and why this interaction will develop into severe inflammatory disease in certain individuals.
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Affiliation(s)
- Robert Blomgran
- Division of Medical Microbiology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden
| | - Veronika Patcha Brodin
- Division of Medical Microbiology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden
| | - Deepti Verma
- Division of Cell Biology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden
| | - Ida Bergström
- Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University, Linköping, Sweden
| | - Peter Söderkvist
- Division of Cell Biology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden
| | - Christopher Sjöwall
- Division of Rheumatology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden
| | - Per Eriksson
- Division of Rheumatology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden
| | - Maria Lerm
- Division of Medical Microbiology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden
- Center for Infectious Medicine, Karolinska Institute Huddinge, Stockholm, Sweden
| | - Olle Stendahl
- Division of Medical Microbiology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden
| | - Eva Särndahl
- Department of Clinical Medicine, School of Health and Medical Sciences, Örebro University, Örebro, Sweden
- * E-mail:
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14
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Edwards DC, McKinnon KM, Fenizia C, Jung KJ, Brady JN, Pise-Masison CA. Inhibition of geranylgeranyl transferase-I decreases cell viability of HTLV-1-transformed cells. Viruses 2011; 3:1815-35. [PMID: 22069517 PMCID: PMC3205383 DOI: 10.3390/v3101815] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 09/26/2011] [Indexed: 12/14/2022] Open
Abstract
Human T-cell leukemia virus type-1 (HTLV-1) is the etiological agent of adult T-cell leukemia (ATL), an aggressive and highly chemoresistant malignancy. Rho family GTPases regulate multiple signaling pathways in tumorigenesis: cytoskeletal organization, transcription, cell cycle progression, and cell proliferation. Geranylgeranylation of Rho family GTPases is essential for cell membrane localization and activation of these proteins. It is currently unknown whether HTLV-1-transformed cells are preferentially sensitive to geranylgeranylation inhibitors, such as GGTI-298. In this report, we demonstrate that GGTI-298 decreased cell viability and induced G2/M phase accumulation of HTLV-1-transformed cells, independent of p53 reactivation. HTLV-1-LTR transcriptional activity was inhibited and Tax protein levels decreased following treatment with GGTI-298. Furthermore, GGTI-298 decreased activation of NF-κB, a downstream target of Rho family GTPases. These studies suggest that protein geranylgeranylation contributes to dysregulation of cell survival pathways in HTLV-1-transformed cells.
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Affiliation(s)
- Dustin C. Edwards
- Virus Tumor Biology Section, Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; E-Mails: (D.C.E.); (K.-J.J.)
| | - Katherine M. McKinnon
- Vaccine Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; E-Mails: (K.M.M.); (C.F.)
| | - Claudio Fenizia
- Vaccine Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; E-Mails: (K.M.M.); (C.F.)
| | - Kyung-Jin Jung
- Virus Tumor Biology Section, Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; E-Mails: (D.C.E.); (K.-J.J.)
| | - John N. Brady
- Virus Tumor Biology Section, Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; E-Mails: (D.C.E.); (K.-J.J.)
| | - Cynthia A. Pise-Masison
- Virus Tumor Biology Section, Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; E-Mails: (D.C.E.); (K.-J.J.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-301-435-2499; Fax: +1-301-496-4951
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15
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Volling K, Thywissen A, Brakhage AA, Saluz HP. Phagocytosis of melanized Aspergillus conidia by macrophages exerts cytoprotective effects by sustained PI3K/Akt signalling. Cell Microbiol 2011; 13:1130-48. [PMID: 21501368 DOI: 10.1111/j.1462-5822.2011.01605.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Host cell death is a critical component of innate immunity and often determines the progression and outcome of infections. The opportunistic human pathogen Aspergillus fumigatus can manipulate the immune system either by inducing or by inhibiting host cell apoptosis dependent on its distinct morphological form. Here, we show that conidia of Aspergillus ssp. inhibit apoptosis of macrophages induced via the intrinsic (staurosporine) and extrinsic (Fas ligand) pathway. Hence, mitochondrial cytochrome c release and caspase activation were prevented. We further found that the anti-apoptotic effect depends on both host cell de novo protein synthesis and phagocytosis of conidia by macrophages. Moreover, sustained PI3K/Akt signalling in infected cells is an important determinant to resist apoptosis. We demonstrate that pigmentless pksP mutant conidia of A. fumigatus failed to trigger protection against apoptosis and provide evidence that the sustained survival of infected macrophages depends on the presence of the grey-green conidial pigment consisting of dihydroxynaphthalene-melanin. In conclusion, we revealed a novel potential function of melanin in the pathogenesis of A. fumigatus. For the first time, we show that melanin itself is a crucial component to inhibit macrophage apoptosis which may contribute to dissemination of the fungus within the host.
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Affiliation(s)
- Katrin Volling
- Department of Cell and Molecular Biology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Beutenbergstrasse 11a, D-07745 Jena, Germany
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16
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Pavlova B, Volf J, Ondrackova P, Matiasovic J, Stepanova H, Crhanova M, Karasova D, Faldyna M, Rychlik I. SPI-1-encoded type III secretion system of Salmonella enterica is required for the suppression of porcine alveolar macrophage cytokine expression. Vet Res 2011; 42:16. [PMID: 21314975 PMCID: PMC3037896 DOI: 10.1186/1297-9716-42-16] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 12/23/2010] [Indexed: 12/02/2022] Open
Abstract
Genes localized at Salmonella pathogenicity island-1 (SPI-1) are involved in Salmonella enterica invasion of host non-professional phagocytes. Interestingly, in macrophages, SPI-1-encoded proteins, in addition to invasion, induce cell death via activation of caspase-1 which also cleaves proIL-1β and proIL-18, precursors of 2 proinflammatory cytokines. In this study we were therefore interested in whether SPI-1-encoded type III secretion system (T3SS) may influence proinflammatory response of macrophages. To test this hypothesis, we infected primary porcine alveolar macrophages with wild-type S. Typhimurium and S. Enteritidis and their isogenic SPI-1 deletion mutants. ΔSPI1 mutants of both serovars invaded approx. 5 times less efficiently than the wild-type strains and despite this, macrophages responded to the infection with ΔSPI1 mutants by increased expression of proinflammatory cytokines IL-1β, IL-8, TNFα, IL-23α and GM-CSF. Identical macrophage responses to that induced by the ΔSPI1 mutants were also observed to the infection with sipB but not the sipA mutant. The hilA mutant exhibited an intermediate phenotype between the ΔSPI1 mutant and the wild-type S. Enteritidis. Our results showed that the SPI-1-encoded T3SS is required not only for cell invasion but in macrophages also for the suppression of early proinflammatory cytokine expression.
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17
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Wang JH, Yu B, He P, Bai X. Roles of Bcl-2 family members, PI3K and NF-κB pathways in Escherichia coli-induced apoptosis in human monocytic U937 cells. World J Microbiol Biotechnol 2010. [DOI: 10.1007/s11274-010-0641-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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18
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Staphylococcus aureus induces apoptosis of human monocytic U937 cells via NF-κB signaling pathways. Microb Pathog 2010; 49:252-9. [DOI: 10.1016/j.micpath.2010.06.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2010] [Revised: 06/07/2010] [Accepted: 06/16/2010] [Indexed: 01/31/2023]
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19
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Bandyopadhaya A, Bhowmick S, Chaudhuri K. Activation of proinflammatory response in human intestinal epithelial cells following Vibrio cholerae infection through PI3K/Akt pathway. Can J Microbiol 2010; 55:1310-8. [PMID: 19940940 DOI: 10.1139/w09-093] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vibrio cholerae activates proinflammatory response in cultured intestinal epithelial cells. In this study, we demonstrate that V. cholerae O395 infection of intestinal epithelial cells results in the activation of Akt. Inhibition of Akt significantly decreases IL-1alpha, IL-6, and TNF-alpha production in V. cholerae infected Int407 cells. Analysis of the mechanisms of Akt influences on cytokine response demonstrates that Akt promotes NF-kappaB activation. We have extended these findings to show that Akt activation may be regulated by bacterial genes associated with virulence, adherence, or motility. Insertion mutants in the virulence genes coding for CtxA, ToxT, and OmpU of V. cholerae modulate the activation of PI3K/Akt signaling pathway, whereas an aflagellate non-motile mutant (O395FLAN) and a adherent and less motile mutant (O395Y3N/O395Y4N) of V. cholerae both show very significant down-regulation of Akt activity in Int407 cells. Together, these observations indicate that Akt promotes proinflammatory cytokine production by V. cholerae infected human intestinal epithelial cells through its influences on NF-kappaB.
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Affiliation(s)
- Arunava Bandyopadhaya
- Molecular & Human Genetics Division, Indian Institute of Chemical Biology, Kolkata-700 032, India
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20
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Shin OS, Miller LS, Modlin RL, Akira S, Uematsu S, Hu LT. Downstream signals for MyD88-mediated phagocytosis of Borrelia burgdorferi can be initiated by TRIF and are dependent on PI3K. THE JOURNAL OF IMMUNOLOGY 2009; 183:491-8. [PMID: 19542460 DOI: 10.4049/jimmunol.0900724] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We previously have shown that MyD88 is important for uptake of Borrelia burgdorferi by bone marrow derived macrophages (BMDMs). The mechanism by which MyD88 is involved in uptake of B. burgdorferi is currently is not well characterized. Here, we report that MyD88-mediated defect in the phagocytosis of B. burgdorferi can be complemented by TLR3/Toll/IL-1R domain-containing adaptor-inducing IFN-beta (TRIF) activation in BMDMs from MyD88(-/-) mice. This effect of TLR3/TRIF activation was not due to its induction of type I IFNs, suggesting instead a convergence of signaling pathways downstream of MyD88 and TRIF. To characterize signaling pathways involved in MyD88-mediated phagocytosis of B. burgdorferi, BMDMs were treated with specific inhibitors of MAPK, protein kinase C, JAK/STAT, or PI3K. Only inhibition of PI3K resulted in a significant decrease of B. burgdorferi uptake. Consistent with this, B. burgdorferi activation of MyD88 or TLR3/TRIF signaling resulted in increased activity of PI3K. Additionally, association of B. burgdorferi with actin-related protein (Arp2/3) complexes, which facilitate actin rearrangements during phagocytosis, was similarly reduced in MyD88(-/-) BMDMs and in BMDMs treated with a PI3K inhibitor. Taken together, these findings define an essential pathway whereby downstream signals from MyD88 or TRIF converge on PI3K, which triggers actin polymerization to initiate the phagocytosis of B. burgdorferi.
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Affiliation(s)
- Ok S Shin
- Department of Pathology/Immunology, Tufts University, Boston, MA 02111, USA
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21
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Persson A, Blomgran-Julinder R, Eklund D, Lundström C, Stendahl O. Induction of apoptosis in human neutrophils by Mycobacterium tuberculosis is dependent on mature bacterial lipoproteins. Microb Pathog 2009; 47:143-50. [PMID: 19501642 DOI: 10.1016/j.micpath.2009.05.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 05/15/2009] [Accepted: 05/27/2009] [Indexed: 10/20/2022]
Abstract
Modulation of immune cell apoptosis is a key evasion strategy utilized by Mycobacterium tuberculosis (Mtb). To be able to multiply within macrophages, the bacterium delays apoptosis and down-regulates pro-inflammatory activation in these cells, whereas apoptosis is rapidly induced in the potently bactericidal neutrophils. Initial host-pathogen interactions between neutrophils and Mtb, subsequently leading to apoptosis, need to be investigated to understand the early features during Mtb infections. Opsonized Mtb were readily phagocytosed, and the immuno-mediated phagocytosis triggered early activation of anti-apoptotic Akt in the neutrophils but the bacteria still induced apoptosis to the same extent as non-phagocytosed Mtb. Mtb-induced apoptosis was strictly dependent on NADPH oxidase-generated reactive oxygen species, compounds shown to damage lysosomal granules. Despite this, we found no involvement of damaged azurophilic granules in Mtb-induced apoptosis in human neutrophils. Instead, the Mtb-induced apoptosis was p38 MAPK dependent and induced through the mitochondrial pathway. Moreover, Mtb deficient of mature lipoproteins lacked the determinants required for induction of neutrophil apoptosis. These results show that Mtb exert a strong intrinsic capacity to induce apoptosis in neutrophils that is capable of overcoming the anti-apoptotic signaling in the cell.
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Affiliation(s)
- Alexander Persson
- Department of Molecular and Clinical Medicine, Linköping University, Sweden.
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22
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Tamilselvam B, Daefler S. Francisella targets cholesterol-rich host cell membrane domains for entry into macrophages. THE JOURNAL OF IMMUNOLOGY 2008; 180:8262-71. [PMID: 18523292 DOI: 10.4049/jimmunol.180.12.8262] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Francisella tularensis is a pathogen optimally adapted to efficiently invade its respective host cell and to proliferate intracellularly. We investigated the role of host cell membrane microdomains in the entry of F. tularensis subspecies holarctica vaccine strain (F. tularensis live vaccine strain) into murine macrophages. F. tularensis live vaccine strain recruits cholesterol-rich lipid domains ("lipid rafts") with caveolin-1 for successful entry into macrophages. Interference with lipid rafts through the depletion of plasma membrane cholesterol, through induction of raft internalization with choleratoxin, or through removal of raft-associated GPI-anchored proteins by treatment with phosphatidylinositol phospholipase C significantly inhibited entry of Francisella and its intracellular proliferation. Lipid raft-associated components such as cholesterol and caveolin-1 were incorporated into Francisella-containing vesicles during entry and the initial phase of intracellular trafficking inside the host cell. These findings demonstrate that Francisella requires cholesterol-rich membrane domains for entry into and proliferation inside macrophages.
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23
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Shiratsuchi H, Basson MD. Akt2, but not Akt1 or Akt3 mediates pressure-stimulated serum-opsonized latex bead phagocytosis through activating mTOR and p70 S6 kinase. J Cell Biochem 2008; 102:353-67. [PMID: 17372934 DOI: 10.1002/jcb.21295] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Monocytes and macrophages play critical roles in innate host defense and are sensitive to mechanical stimuli. Tissue pressure is often altered in association with inflammation or infection. Low pressure (20 mmHg), equivalent to normal tissue pressure, increases phagocytosis by primary monocytes and PMA-differentiated THP-1 macrophages, in part by FAK and ERK inhibition and p38 activation. PI-3K is required for macrophage phagocytosis, but whether PI-3K mediates pressure-stimulated phagocytosis is not known. Furthermore, little is known about the role played by the PI-3K downstream Kinases, Akt, and p70 S6 kinase (p70S6K) in modulating macrophage phagocytosis. Thus, we studied the contribution of PI-3K, Akt, and p70S6K to pressure-increased serum-opsonized bead phagocytosis. Pressure-induced p85 PI-3K translocation from cytosolic to membrane fractions and increased Akt activation by 36.1 +/- 12.0% in THP-1 macrophages. LY294002 or Akt inhibitor IV abrogated pressure-stimulated but not basal phagocytosis. Basal Akt activation was inhibited 90% by LY294002 and 70% by Akt inhibitor IV. Each inhibitor prevented Akt activation by pressure. SiRNA targeted to Akt1, Akt2, or Akt3 reduced Akt1, Akt2, and Akt3 expression by 50%, 45%, and 40%, respectively. However, only Akt2SiRNA abrogated the pressure-stimulated phagocytosis without affecting basal. Pressure also activated mTOR and p70S6K. mTORSiRNA and p70S6K inhibition by rapamycin or p70S6KSiRNA blocked pressure-induced, but not basal, phagocytosis. Changes in tissue pressure during inflammation may regulate macrophage phagocytosis by activation of PI-3K, which activates Akt2, mTOR, and p70S6K.
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Affiliation(s)
- Hiroe Shiratsuchi
- Department of Surgery, Wayne State University, School of Medicine, and John D. Dingell VA Medical Center, Detroit, Michigan 48201, USA.
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Blomgran R, Zheng L, Stendahl O. Cathepsin-cleaved Bid promotes apoptosis in human neutrophils via oxidative stress-induced lysosomal membrane permeabilization. J Leukoc Biol 2007; 81:1213-23. [PMID: 17264306 DOI: 10.1189/jlb.0506359] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Lysosomal membrane permeabilization (LMP) is emerging as an important regulator of cell apoptosis. Human neutrophils are highly granulated phagocytes, which respond to pathogens by exhibiting increased production of reactive oxygen species (ROS) and lysosomal degranulation. In a previous study, we observed that intracellular, nonphagosomal generation of ROS triggered by adherent bacteria induced ROS-dependent neutrophil apoptosis, whereas intraphagosomal production of ROS during phagocytosis had no effect. In the present study, we measured lysosomal membrane stability and leakage in human neutrophils and found that adherent, noningested, Type 1-fimbriated Escherichia coli bacteria induced LMP rapidly in neutrophils. Pretreatment with the NADPH oxidase inhibitor diphenylene iodonium markedly blocked the early LMP and apoptosis in neutrophils stimulated with Type 1-fimbriated bacteria but had no effect on the late LMP seen in spontaneously apoptotic neutrophils. The induced lysosomal destabilization triggered cleavage of the proapoptotic Bcl-2 protein Bid, followed by a decrease in the antiapoptotic protein Mcl-1. Involvement of LMP in initiation of apoptosis is supported by the following observations: Bid cleavage and the concomitant drop in mitochondrial membrane potential required activation of cysteine-cathepsins but not caspases, and the differential effects of inhibitors of cysteine-cathepsins and cathepsin D on apoptosis coincided with their ability to inhibit Bid cleavage in activated neutrophils. Together, these results indicate that in microbe-induced apoptosis in neutrophils, ROS-dependent LMP represents an early event in initiation of the intrinsic apoptotic pathway, which is followed by Bid cleavage, mitochondrial damage, and caspase activation.
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Affiliation(s)
- Robert Blomgran
- Department of Molecular and Clinical Medicine, Faculty of Health Sciences, Linköping University, SE-581 85, Linköping, Sweden.
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25
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Wang JH, Zhou YJ, He P, Chen BY. Roles of mitogen-activated protein kinase pathways during Escherichia coli-induced apoptosis in U937 cells. Apoptosis 2006; 12:375-85. [PMID: 17191113 DOI: 10.1007/s10495-006-0623-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Escherichia coli (E. coli) infections play an important and growing role in the clinic. In the present study, we investigated the involvement of members of the mitogen-activated protein kinase (MAPK) superfamily, including extracellular signal-regulated kinase (ERK), c-Jun NH(2)-terminal kinase (JNK) and p38 MAPK, and caspase-3 and 9 activity in E. coli-induced apoptosis in human U937 cells. We found that E. coli induces apoptosis in U937 cell lines in a dose- and time-dependent manner, p38 MAPK and JNK were activated after 10 min of infection with E. coli. In contrast, ERK1/2 was down-regulated in a time-dependent manner. The levels of total (phosphorylation state-independent) p38 MAPK, JNK and ERK1/2 did not change in E. coli-infected U937 cells at all times examined. Moreover, exposure of U937 cells to E. coli led to caspase-3 and 9 activity. For the evaluation of the role of MAPKs, PD98059, SB203580 and SP600125 were used as MAPKs inhibitors for ERK1/2, p38 MAPK and JNK. Inhibition of ERK1/2 with PD98059 caused further enhancement in apoptosis and caspase-3 and 9 activity, while a selective p38 MAPK inhibitor, SB203580 and JNK inhibitor, SP600125 significantly inhibited E. coli-induced apoptosis and caspase-3 and 9 activity in U937 cells. The results were further confirmed by the observation that the caspase inhibitors Z-DEVD-FMK and Z-LEHD-FMK blocked E. coli-induced U937 apoptosis. Taken together, we have shown that E. coli increase p38 MAPK and JNK and decrease ERK1/2 phosphorylation and increase caspase-3 and 9 activity in U937 cells.
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Affiliation(s)
- J H Wang
- Department of Geriatrics, The Second Affiliated Hospital, China Medical University, Shenyang, P.R. China
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Khwaja A, Sharpe CC, Noor M, Hendry BM. The role of geranylgeranylated proteins in human mesangial cell proliferation. Kidney Int 2006; 70:1296-304. [PMID: 16929252 DOI: 10.1038/sj.ki.5001713] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The Rho family of guanine 5'-triphosphatases (GTPases) play a key role in regulating cell proliferation, tubulointerstitial fibrosis, and glomerular hemodynamics. The post-translational prenylation of RhoGTPases by the addition of a geranylgeranyl moiety is critical for cellular localization and signaling activity. This study investigates the effects of (i) inhibiting geranylgeranylation (GG) in human mesangial cell (HMC) proliferation and apoptosis, using GGTI 298, a specific inhibitor of GG and (ii) lovastatin, an HMG-coacetyl A-reductase inhibitor, which depletes the availability of prenylation substrates. HMC proliferation was assessed using an assay of viable cell number and measuring bromodeoxyuridine (BrdU) incorporation. Hoechst 33342 staining was used to determine apoptosis. Extracellular signal-regulated protein kinase (Erk)1/2 and Akt activation were analysed by Western blotting. Rho activation was determined using the Rhotekin pull-down assay. Immunocytochemistry was performed to study the effects on the actin cytoskeleton and RhoA localization. GGTI 298 (10-20 muM) and lovastatin (5-10 muM) potently inhibited platelet-derived growth factor and serum-stimulated HMC proliferation and induced apoptosis. These effects of lovastatin were attenuated by co-incubation with geranylgeranylpyrophosphate. C3 exoenzyme, a clostridial toxin that specifically targets Rho also inhibited BrdU incorporation and promoted apoptosis. GGTI 298 increased cytosolic expression of RhoA, prevented RhoA activation, and inhibited the activation of Erk1/2 and the survival protein Akt. GGTI 298, lovastatin, and C3 exoenzyme inhibit HMC proliferation and promote apoptosis. Inhibiting GG increases cytosolic RhoA expression, disrupts the actin cytoskeleton, and inhibits RhoA activation. These results suggest that targeting geranylgeranylated proteins with statins or GGTI 298 is a promising therapeutic strategy in human mesangioproliferative renal disease.
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Affiliation(s)
- A Khwaja
- Department of Renal Medicine, GKT School of Medicine, King's College London, Bessemer Road, London, UK
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Salmonella and Enteropathogenic Escherichia coli Interactions with Host Cells: Signaling Pathways. EcoSal Plus 2006; 2. [PMID: 26443572 DOI: 10.1128/ecosalplus.8.8.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The host-pathogen interaction involves a myriad of initiations and responses from both sides. Bacterial pathogens such as enteropathogenic Escherichia coli (EPEC) and Salmonella enterica have numerous virulence factors that interact with and alter signaling components of the host cell to initiate responses that are beneficial to pathogen survival and persistence. The study of Salmonella and EPEC infection reveals intricate connections between host signal transduction, cytoskeletal architecture, membrane trafficking, and cytokine gene expression. The emerging picture includes elements of molecular mimicry by bacterial effectors and bacterial subversion of typical host events, with the result that EPEC is able to survive and persist in an extracellular milieu, while Salmonella establishes an intracellular niche and is able to spread systemically throughout the host. This review focuses on recent advances in our understanding of the signaling events stemming from the host-pathogen interactions specific to Salmonella and EPEC.
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Boyen F, Pasmans F, Donné E, Van Immerseel F, Adriaensen C, Hernalsteens JP, Ducatelle R, Haesebrouck F. Role of SPI-1 in the interactions of Salmonella Typhimurium with porcine macrophages. Vet Microbiol 2005; 113:35-44. [PMID: 16310983 DOI: 10.1016/j.vetmic.2005.10.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2005] [Revised: 10/04/2005] [Accepted: 10/06/2005] [Indexed: 12/11/2022]
Abstract
Salmonella Pathogenicity Island 1 (SPI-1) genes are indispensable for virulence of Salmonella Typhimurium in mice after oral challenge. These genes mediate invasion in intestinal epithelial cells and induce cell death in murine macrophages. The role of SPI-1 in the pathogenesis of Salmonella Typhimurium infections in food producing animals is not known. It was the aim of the present study to characterize the interactions of a porcine Salmonella Typhimurium field strain and its isogenic mutants in the SPI-1 genes hilA, sipA and sipB with porcine macrophages. SPI-1 was found to be important in the invasion of porcine pulmonary alveolar macrophages (PAM) and the induction of the formation of spacious phagosomes. Both early and delayed cytotoxicity were seen in PAM, but only the early cytotoxicity was SPI-1 dependent. Exposure of PAM to Salmonella Typhimurium induced the production of reactive oxygen species (ROS) and interleukin-8, but no differences were noticed between the induction mediated by the wild type strain and its SPI-1 mutant strains. In conclusion, invasion of porcine macrophages and the induction of early, but not delayed, cytotoxicity by Salmonella Typhimurium is SPI-1 dependent. SPI-1 dependent invasion, however, is not a prerequisite to induce a pro-inflammatory response.
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Affiliation(s)
- F Boyen
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
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Intracellular Voyeurism: Examining the Modulation of Host Cell Activities bySalmonella enterica Serovar Typhimurium. EcoSal Plus 2005; 1. [PMID: 26443522 DOI: 10.1128/ecosalplus.2.2.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Salmonella spp. can infect host cells by gaining entry through phagocytosis or by inducing host cell membrane ruffling that facilitates bacterial uptake. With its wide host range, Salmonella enterica serovar Typhimurium has proven to be an important model organism for studying intracellular bacterial pathogenesis. Upon entry into host cells, serovar Typhimurium typically resides within a membrane-bound compartment termed the Salmonella-containing vacuole (SCV). From the SCV, serovar Typhimurium can inject several effector proteins that subvert many normal host cell systems, including endocytic trafficking, cytoskeletal rearrangements, lipid signaling and distribution, and innate and adaptive host defenses. The study of these intracellular events has been made possible through the use of various imaging techniques, ranging from classic methods of transmission electron microscopy to advanced livecell fluorescence confocal microscopy. In addition, DNA microarrays have now been used to provide a "snapshot" of global gene expression in serovar Typhimurium residing within the infected host cell. This review describes key aspects of Salmonella-induced subversion of host cell activities, providing examples of imaging that have been used to elucidate these events. Serovar Typhimurium engages specific host cell machinery from initial contact with the host cell to replication within the SCV. This continuous interaction with the host cell has likely contributed to the extensive arsenal that serovar Typhimurium now possesses, including two type III secretion systems, a range of ammunition in the form of TTSS effectors, and a complex genetic regulatory network that coordinates the expression of hundreds of virulence factors.
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Allen LAH, Allgood JA, Han X, Wittine LM. Phosphoinositide3-kinase regulates actin polymerization during delayed phagocytosis of Helicobacter pylori. J Leukoc Biol 2005; 78:220-30. [PMID: 15809290 PMCID: PMC1868428 DOI: 10.1189/jlb.0205091] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We have shown previously that ulcerogenic (type I) strains of Helicobacter pylori (Hp) retard their entry into macrophages. However, the signaling pathways that regulate Hp phagocytosis are largely undefined. We show here that Hp strongly activated class IA phosphoinositide3-kinases (PI3Ks) in macrophages, coincident with phagocytosis, and endogenous p85 and active protein kinase Balpha accumulated on forming phagosomes. PI3K inhibitors, wortmannin and LY294002, inhibited phagocytosis of Hp in a dose-dependent manner, and blockade of engulfment correlated directly with loss of 3'-phosphoinositides in the membrane subjacent to attached bacteria. During uptake of large immunoglobulin G (IgG)-coated particles, PI3Ks regulate pseudopod extension and phagosome closure. In marked contrast, we show here that 3'-phosphoinositides regulated actin polymerization at sites of Hp uptake. Moreover, Hp and IgG beads activated distinct PI3K isoforms. Phagosomes containing IgG-coated particles accumulated 3'-phosphatase and tensin homologue deleted on chromosome 10 and Src homology 2 domain-containing inositol 5'-phosphatase, yet Hp phagosomes did not. Finally, rapid uptake of IgG-opsonized Hp or a less-virulent type II Hp was PI3K-independent. We conclude that Hp and IgG beads are ingested by distinct mechanisms and that PI3Ks regulate the actin cytoskeleton during slow phagocytosis of ulcerogenic Hp.
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Affiliation(s)
- Lee-Ann H Allen
- Department of Medicine, University of Iowa, Coralville, 52241, USA.
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Huang FC, Li Q, Cherayil BJ. A phosphatidyl-inositol-3-kinase-dependent anti-inflammatory pathway activated by Salmonella in epithelial cells. FEMS Microbiol Lett 2005; 243:265-70. [PMID: 15668028 DOI: 10.1016/j.femsle.2004.12.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Revised: 12/10/2004] [Accepted: 12/12/2004] [Indexed: 11/19/2022] Open
Abstract
Salmonella activates the phosphatidyl-inositol-3-kinase (PI3K)/Akt pathway in epithelial cells, but its role in inflammation has not been previously elucidated. We show here that inhibition of PI3K in T84 intestinal epithelial cells results in augmentation of Salmonella-induced interleukin-8 (IL-8) production at the level of both protein and mRNA. The mechanism of this effect appears to involve altered activation of the extracellular growth factor-regulated kinase (ERK), a molecule that is implicated in the regulation of IL-8 expression. These results identify activation of the PI3K/Akt pathway as an anti-inflammatory signal that may contribute to the establishment of Salmonella in the intestine.
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Affiliation(s)
- Fu-Chen Huang
- Department of Pediatrics, Pediatric Gastroenterology and Nutrition Unit, Massachusetts General Hospital, Charlestown, MA 02129, USA
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Ohya K, Handa Y, Ogawa M, Suzuki M, Sasakawa C. IpgB1 is a novel Shigella effector protein involved in bacterial invasion of host cells. Its activity to promote membrane ruffling via Rac1 and Cdc42 activation. J Biol Chem 2005; 280:24022-34. [PMID: 15849186 DOI: 10.1074/jbc.m502509200] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Shigella, the causative agent of bacillary dysentery, is capable of inducing the large scale membrane ruffling required for the bacterial invasion of host cells. Shigella secrete a subset of effectors via the type III secretion system (TTSS) into the host cells to induce membrane ruffling. Here, we show that IpgB1 is secreted via the TTSS into epithelial cells and plays a major role in producing membrane ruffles via stimulation of Rac1 and Cdc42 activities, thus promoting bacterial invasion of epithelial cells. The invasiveness of the ipgB1 mutant was decreased to less than 50% of the wild-type level (100%) in a gentamicin protection or plaque forming assay. HeLa cells infected with the wild-type or a IpgB1-hyperproducing strain developed membrane ruffles, with the invasiveness and the scale of membrane ruffles being comparable with the level of IpgB1 production in bacteria. Upon expression of EGFP-IpgB1 in HeLa cells, large membrane ruffles are extended, where the EGFP-IpgB1 was predominantly associated with the cytoplasmic membrane. The IpgB1-mediated formation of ruffles was significantly diminished by expressing Rac1 small interfering RNA and Cdc42 small interfering RNA or by treatment with GGTI-298, an inhibitor of the geranylgeranylation of Rho GTPases. When IpgB1 was expressed in host cells or wild-type Shigella-infected host cells, Rac1 and Cdc42 were activated. The results thus indicate that IpgB1 is a novel Shigella effector involved in bacterial invasion of epithelial cells via the activation of Rho GTPases.
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Affiliation(s)
- Kenji Ohya
- Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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Abstract
The facultative intracellular pathogen Salmonella enterica triggers programmed cell death in macrophages. The close examination of this phenomenon has revealed an unusually complex picture involving diverse mechanisms that lead to different types of programmed cell death. It appears that the outcome of the interaction of salmonella with macrophages depends on the relative contribution of two type III protein secretion systems, in conjunction with the stimulation of innate immunity outputs through conserved determinants collectively known as 'pathogen-associated molecular patterns' (PAMPs). These interactions result in a breakdown of the balance between survival and pro-apoptotic cellular pathways, which eventually leads to macrophage cell death. The relative significance for the infection process of the different types of macrophage cell death triggered by salmonella remains to be established.
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Affiliation(s)
- Karsten Hueffer
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
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Blomgran R, Zheng L, Stendahl O. Uropathogenic Escherichia coli triggers oxygen-dependent apoptosis in human neutrophils through the cooperative effect of type 1 fimbriae and lipopolysaccharide. Infect Immun 2004; 72:4570-8. [PMID: 15271917 PMCID: PMC470702 DOI: 10.1128/iai.72.8.4570-4578.2004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Type 1 fimbriae are the most commonly expressed virulence factor on uropathogenic Escherichia coli. In addition to promoting avid bacterial adherence to the uroepithelium and enabling colonization, type 1 fimbriae recruit neutrophils to the urinary tract as an early inflammatory response. Using clinical isolates of type 1 fimbriated E. coli and an isogenic type 1 fimbria-negative mutant (CN1016) lacking the FimH adhesin, we investigated if these strains could modulate apoptosis in human neutrophils. We found that E. coli expressing type 1 fimbriae interacted with neutrophils in a mannose- and lipopolysaccharide (LPS)-dependent manner, leading to apoptosis which was triggered by the intracellular generation of reactive oxygen species. This induced neutrophil apoptosis was abolished by blocking FimH-mediated attachment, by inhibiting NADPH oxidase activation, or by neutralizing LPS. In contrast, CN1016, which did not adhere to or activate the respiratory burst of neutrophils, delayed the spontaneous apoptosis in an LPS-dependent manner. This delayed apoptosis could be mimicked by adding purified LPS and was also observed by using fimbriated bacteria in the presence of d-mannose. These results suggest that LPS is required for E. coli to exert both pro- and antiapoptotic effects on neutrophils and that the difference in LPS presentation (i.e., with or without fimbriae) determines the outcome. The present study showed that there is a fine-tuned balance between type 1 fimbria-induced and LPS-mediated delay of apoptosis in human neutrophils, in which altered fimbrial expression on uropathogenic E. coli determines the neutrophil survival and the subsequent inflammation during urinary tract infections.
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Affiliation(s)
- Robert Blomgran
- Division of Medical Microbiology, Department of Molecular and Clinical Medicine, Faculty of Health Sciences, Linköping University, Linkoping, Sweden.
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Yilmaz O, Jungas T, Verbeke P, Ojcius DM. Activation of the phosphatidylinositol 3-kinase/Akt pathway contributes to survival of primary epithelial cells infected with the periodontal pathogen Porphyromonas gingivalis. Infect Immun 2004; 72:3743-51. [PMID: 15213114 PMCID: PMC427421 DOI: 10.1128/iai.72.7.3743-3751.2004] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Porphyromonas gingivalis, an important periodontal pathogen, infects primary gingival epithelial cells (GECs). Despite the large number of bacteria that replicate inside the GECs, the host cell remains viable. We demonstrate that P. gingivalis triggers rapid and reversible surface phosphatidylserine exposure through a mechanism requiring caspase activation. However, after 1 day of infection, the bacteria no longer induce phosphatidylserine externalization and instead protect infected cells against apoptosis. Infection exerts its effect at the level of mitochondria, as P. gingivalis also blocks depolarization of the mitochondrial transmembrane potential and cytochrome c release. Interestingly, protein kinase B/Akt is phosphorylated during infection, which can be blocked with the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. Suppression of the PI3K/Akt pathway following staurosporine treatment results in mitochondrial-membrane depolarization, cytochrome c release, DNA fragmentation, and increased apoptosis of infected GECs. Thus, P. gingivalis stimulates early surface exposure of phosphatidylserine, which could downmodulate the inflammatory response, while also promoting host cell survival through the PI3K/Akt pathway.
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Affiliation(s)
- Ozlem Yilmaz
- Department of Pathobiology, University of Washington, School of Public Health, HSC Box 357238, Seattle, WA 98195, USA.
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