1
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Arnold C, Ellwanger K, Kufer TA. Analysis of the Localization of NLRs upon Shigella flexneri Infection Exemplified by NOD1. Methods Mol Biol 2022; 2421:37-56. [PMID: 34870810 DOI: 10.1007/978-1-0716-1944-5_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
NOD-like receptors (NLRs) are a family of pattern recognition receptors, able to respond to conserved microbial structures and endogenous danger signals. The NLR NOD1 responds to bacterial peptidoglycan, leading to recruitment of RIPK2, following activation of NFκB and MAPK pathways. In this chapter, we describe a fluorescent light microscopic approach to analyze the subcellular distribution of NOD1 upon infection with the invasive, Gram-negative bacterial pathogen Shigella flexneri. This method is based on exogenously expressed EGFP-tagged NOD1 and describes a protocol to obtain inducible cell lines with functional NOD1 signaling. The described protocol is useful to study NOD1 function, also in living cells, using live cell imaging and can be adopted for the study of other NLR proteins.
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Affiliation(s)
- Christine Arnold
- Department of Immunology, Institute of Nutritional Medicine, University of Hohenheim, Stuttgart, Germany
| | - Kornelia Ellwanger
- Department of Immunology, Institute of Nutritional Medicine, University of Hohenheim, Stuttgart, Germany
| | - Thomas A Kufer
- Department of Immunology, Institute of Nutritional Medicine, University of Hohenheim, Stuttgart, Germany.
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2
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Identification of Autophagy-Related Genes in the Potato Psyllid, Bactericera cockerelli and Their Expression Profile in Response to ' Candidatus Liberibacter Solanacearum' in the Gut. INSECTS 2021; 12:insects12121073. [PMID: 34940161 PMCID: PMC8708441 DOI: 10.3390/insects12121073] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/19/2021] [Accepted: 11/26/2021] [Indexed: 12/13/2022]
Abstract
Simple Summary In North America, the bacterial plant pathogen ‘Candidatus Liberibacter solanacearum’ (Lso) infects solanaceous plants. Currently, Lso haplotypes, LsoA and LsoB are transmitted by potato psyllid, Bactericera cockerelli (Šulc). Because these bacteria are transmitted in a circulative and persistent manner, the gut of the psyllid is the first organ they encounter and could be a barrier to its transmission. Therefore, it is important to understand the molecular mechanisms involved in Lso acquisition and transmission. This study explored if an autophagic response was triggered in response to LsoA and/or LsoB in the gut of the adult potato psyllid. The results showed that Lso may induce the autophagic response in the adult psyllid gut since the majority of autophagy-related genes (ATGs) are sensitive and responsive to the exposure or infection of both LsoA and LsoB. Therefore, this study represents a stepping-stone towards understanding the molecular mechanisms involved in Lso transmission. Abstract Autophagy, also known as type II programmed cell death, is a cellular mechanism of “self-eating”. Autophagy plays an important role against pathogen infection in numerous organisms. Recently, it has been demonstrated that autophagy can be activated and even manipulated by plant viruses to facilitate their transmission within insect vectors. However, little is known about the role of autophagy in the interactions of insect vectors with plant bacterial pathogens. ‘Candidatus Liberibacter solanacearum’ (Lso) is a phloem-limited Gram-negative bacterium that infects crops worldwide. Two Lso haplotypes, LsoA and LsoB, are transmitted by the potato psyllid, Bactericera cockerelli and cause damaging diseases in solanaceous plants (e.g., zebra chip in potatoes). Both LsoA and LsoB are transmitted by the potato psyllid in a persistent circulative manner: they colonize and replicate within psyllid tissues. Following acquisition, the gut is the first organ Lso encounters and could be a barrier for transmission. In this study, we annotated autophagy-related genes (ATGs) from the potato psyllid transcriptome and evaluated their expression in response to Lso infection at the gut interface. In total, 19 ATGs belonging to 17 different families were identified. The comprehensive expression profile analysis revealed that the majority of the ATGs were regulated in the psyllid gut following the exposure or infection to each Lso haplotype, LsoA and LsoB, suggesting a potential role of autophagy in response to Lso at the psyllid gut interface.
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3
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Soe YM, Bedoui S, Stinear TP, Hachani A. Intracellular Staphylococcus aureus and host cell death pathways. Cell Microbiol 2021; 23:e13317. [PMID: 33550697 DOI: 10.1111/cmi.13317] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 01/22/2021] [Accepted: 01/23/2021] [Indexed: 12/13/2022]
Abstract
Staphylococcus aureus is a major opportunistic human pathogen that is globally prevalent. Although S. aureus and humans may have co-evolved to the point of commensalism, the bacterium is equipped with virulence factors causing devastating infections. The adoption of an intracellular lifestyle by S. aureus is an important facet of its pathogenesis. Occupying a privileged intracellular compartment permits evasion from the bactericidal actions of host immunity and antibiotics. However, this localization exposes S. aureus to cell-intrinsic processes comprising autophagy, metabolic challenges and clearance mechanisms orchestrated by host programmed cell death pathways (PCDs), including apoptosis, pyroptosis and necroptosis. Mounting evidence suggests that S. aureus deploys pathoadaptive mechanisms that modulate the expression of its virulence factors to prevent elimination through PCD pathways. In this review, we critically analyse the current literature on the interplay between S. aureus virulence factors with the key, intertwined nodes of PCD. We discuss how S. aureus adaptation to the human host plays an essential role in the evasion of PCD, and we consider future directions to study S. aureus-PCD interactions.
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Affiliation(s)
- Ye Mon Soe
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Sammy Bedoui
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Timothy P Stinear
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Abderrahman Hachani
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
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4
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Autophagy-A Story of Bacteria Interfering with the Host Cell Degradation Machinery. Pathogens 2021; 10:pathogens10020110. [PMID: 33499114 PMCID: PMC7911818 DOI: 10.3390/pathogens10020110] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 02/07/2023] Open
Abstract
Autophagy is a highly conserved and fundamental cellular process to maintain cellular homeostasis through recycling of defective organelles or proteins. In a response to intracellular pathogens, autophagy further acts as an innate immune response mechanism to eliminate pathogens. This review will discuss recent findings on autophagy as a reaction to intracellular pathogens, such as Salmonella typhimurium, Listeria monocytogenes, Mycobacterium tuberculosis, Staphylococcus aureus, and pathogenic Escherichia coli. Interestingly, while some of these bacteria have developed methods to use autophagy for their own benefit within the cell, others have developed fascinating mechanisms to evade recognition, to subvert the autophagic pathway, or to escape from autophagy.
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5
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The Role of Autophagy and Autophagy Receptor NDP52 in Microbial Infections. Int J Mol Sci 2020; 21:ijms21062008. [PMID: 32187990 PMCID: PMC7139735 DOI: 10.3390/ijms21062008] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 03/05/2020] [Accepted: 03/12/2020] [Indexed: 01/04/2023] Open
Abstract
Autophagy is a general protective mechanism for maintaining homeostasis in eukaryotic cells, regulating cellular metabolism, and promoting cell survival by degrading and recycling cellular components under stress conditions. The degradation pathway that is mediated by autophagy receptors is called selective autophagy, also named as xenophagy. Autophagy receptor NDP52 acts as a ‘bridge’ between autophagy and the ubiquitin-proteasome system, and it also plays an important role in the process of selective autophagy. Pathogenic microbial infections cause various diseases in both humans and animals, posing a great threat to public health. Increasing evidence has revealed that autophagy and autophagy receptors are involved in the life cycle of pathogenic microbial infections. The interaction between autophagy receptor and pathogenic microorganism not only affects the replication of these microorganisms in the host cell, but it also affects the host’s immune system. This review aims to discuss the effects of autophagy on pathogenic microbial infection and replication, and summarizes the mechanisms by which autophagy receptors interact with microorganisms. While considering the role of autophagy receptors in microbial infection, NDP52 might be a potential target for developing effective therapies to treat pathogenic microbial infections.
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6
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Cai J, Li J, Zhou Y, Wang J, Li J, Cui L, Meng X, Zhu G, Wang H. Staphylococcus aureus facilitates its survival in bovine macrophages by blocking autophagic flux. J Cell Mol Med 2020; 24:3460-3468. [PMID: 31997584 PMCID: PMC7131951 DOI: 10.1111/jcmm.15027] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 12/16/2019] [Accepted: 01/13/2020] [Indexed: 12/16/2022] Open
Abstract
Staphylococcus aureus is a pathogen that is the causative agent of several human and veterinary infections and plays a critical role in the clinical and subclinical mastitis of cattle. Autophagy is a conserved pathogen defence mechanism in eukaryotes. Studies have reported that S aureus can subvert autophagy and survive in cells. Staphylococcus aureus survival in cells is an important cause of chronic persistent mastitis infection. However, it is unclear whether S aureus can escape autophagy in innate immune cells. In this study, initiation of autophagy due to the presence of S aureus was detected in bovine macrophages. We observed autophagic vacuoles increased after S aureus infection of bovine macrophages by transmission electron microscopy (TEM). It was also found that S aureus‐infected bovine macrophages increased the expression of LC3 at different times(0, 0.5, 1, 1.5, 2, 2.5, 3 and 4 hours). Data also showed the accumulation of p62 induced by S aureus infection. Application of autophagy regulatory agents showed that the degradation of p62 was blocked in S aureus induced bovine macrophages. In addition, we also found that the accumulation of autophagosomes promotes S aureus to survive in macrophage cells. In conclusion, this study indicates that autophagy occurs in S aureus‐infected bovine macrophages but is blocked at a later stage of autophagy. The accumulation of autophagosomes facilitates the survival of S aureus in bovine macrophages. These findings provide new insights into the interaction of S aureus with autophagy in bovine macrophages.
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Affiliation(s)
- Juan Cai
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Jun Li
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Yuqi Zhou
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Jianqiang Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Jianji Li
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Luying Cui
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Xia Meng
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Guoqiang Zhu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Heng Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
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7
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Zhang F, Chen C, Hu J, Su R, Zhang J, Han Z, Chen H, Li Y. Molecular mechanism of Helicobacter pylori-induced autophagy in gastric cancer. Oncol Lett 2019; 18:6221-6227. [PMID: 31788098 DOI: 10.3892/ol.2019.10976] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 07/26/2019] [Indexed: 12/14/2022] Open
Abstract
Helicobacter pylori (H. pylori) is a gram-negative pathogen that colonizes gastric epithelial cells. The drug resistance rates of H. pylori have dramatically increased, causing persistent infections. Chronic infection by H. pylori is a critical cause of gastritis, peptic ulcers and even gastric cancer. In host cells, autophagy is stimulated to maintain cellular homeostasis following intracellular pathogen recognition by the innate immune defense system. However, H. pylori-induced autophagy is not consistent during acute and chronic infection. Therefore, a deeper understanding of the association between H. pylori infection and autophagy in gastric epithelial cells could aid the understanding of the mechanisms of persistent infection and the identification of autophagy-associated therapeutic targets for H. pylori infection. The present review describes the role of H. pylori and associated virulence factors in the induction of autophagy by different signaling pathways during acute infection. Additionally, the inhibition of autophagy in gastric epithelial cells during chronic infection was discussed. The present review summarized H. pylori-mediated autophagy and provided insights into its mechanism of action, suggesting the induction of autophagy as a novel therapeutic target for persistent H. pylori infection.
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Affiliation(s)
- Fan Zhang
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Cong Chen
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Jike Hu
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Ruiliang Su
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Junqiang Zhang
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Zhijian Han
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Hao Chen
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Yumin Li
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
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8
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Khandia R, Dadar M, Munjal A, Dhama K, Karthik K, Tiwari R, Yatoo MI, Iqbal HMN, Singh KP, Joshi SK, Chaicumpa W. A Comprehensive Review of Autophagy and Its Various Roles in Infectious, Non-Infectious, and Lifestyle Diseases: Current Knowledge and Prospects for Disease Prevention, Novel Drug Design, and Therapy. Cells 2019; 8:cells8070674. [PMID: 31277291 PMCID: PMC6678135 DOI: 10.3390/cells8070674] [Citation(s) in RCA: 145] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/04/2019] [Accepted: 06/04/2019] [Indexed: 02/05/2023] Open
Abstract
Autophagy (self-eating) is a conserved cellular degradation process that plays important roles in maintaining homeostasis and preventing nutritional, metabolic, and infection-mediated stresses. Autophagy dysfunction can have various pathological consequences, including tumor progression, pathogen hyper-virulence, and neurodegeneration. This review describes the mechanisms of autophagy and its associations with other cell death mechanisms, including apoptosis, necrosis, necroptosis, and autosis. Autophagy has both positive and negative roles in infection, cancer, neural development, metabolism, cardiovascular health, immunity, and iron homeostasis. Genetic defects in autophagy can have pathological consequences, such as static childhood encephalopathy with neurodegeneration in adulthood, Crohn's disease, hereditary spastic paraparesis, Danon disease, X-linked myopathy with excessive autophagy, and sporadic inclusion body myositis. Further studies on the process of autophagy in different microbial infections could help to design and develop novel therapeutic strategies against important pathogenic microbes. This review on the progress and prospects of autophagy research describes various activators and suppressors, which could be used to design novel intervention strategies against numerous diseases and develop therapeutic drugs to protect human and animal health.
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Affiliation(s)
- Rekha Khandia
- Department of Genetics, Barkatullah University, Bhopal 462 026, Madhya Pradesh, India
| | - Maryam Dadar
- Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj 31975/148, Iran
| | - Ashok Munjal
- Department of Genetics, Barkatullah University, Bhopal 462 026, Madhya Pradesh, India.
| | - Kuldeep Dhama
- Division of Pathology, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly 243 122, Uttar Pradesh, India.
| | - Kumaragurubaran Karthik
- Central University Laboratory, Tamil Nadu Veterinary and Animal Sciences University, Madhavaram Milk Colony, Chennai, Tamil Nadu 600051, India
| | - Ruchi Tiwari
- Department of Veterinary Microbiology and Immunology, College of Veterinary Sciences, UP Pandit Deen Dayal Upadhayay Pashu Chikitsa Vigyan Vishwavidyalay Evum Go-Anusandhan Sansthan (DUVASU), Mathura, Uttar Pradesh 281 001, India
| | - Mohd Iqbal Yatoo
- Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, Shalimar, Srinagar 190025, Jammu and Kashmir, India
| | - Hafiz M N Iqbal
- Tecnologico de Monterrey, School of Engineering and Sciences, Campus Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N. L., CP 64849, Mexico
| | - Karam Pal Singh
- Division of Pathology, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly 243 122, Uttar Pradesh, India
| | - Sunil K Joshi
- Department of Pediatrics, Division of Hematology, Oncology and Bone Marrow Transplantation, University of Miami School of Medicine, Miami, FL 33136, USA.
| | - Wanpen Chaicumpa
- Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
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9
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Abstract
ABSTRACT
Shigella
is a genus of Gram-negative enteropathogens that have long been, and continue to be, an important public health concern worldwide. Over the past several decades,
Shigella
spp. have also served as model pathogens in the study of bacterial pathogenesis, and
Shigella flexneri
has become one of the best-studied pathogens on a molecular, cellular, and tissue level. In the arms race between
Shigella
and the host immune system,
Shigella
has developed highly sophisticated mechanisms to subvert host cell processes in order to promote infection, escape immune detection, and prevent bacterial clearance. Here, we give an overview of
Shigella
pathogenesis while highlighting innovative techniques and methods whose application has significantly advanced our understanding of
Shigella
pathogenesis in recent years.
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10
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Human Intestinal Enteroids as a Model System of Shigella Pathogenesis. Infect Immun 2019; 87:IAI.00733-18. [PMID: 30642906 DOI: 10.1128/iai.00733-18] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 01/06/2019] [Indexed: 01/01/2023] Open
Abstract
The enteric bacterium and intracellular human pathogen Shigella causes hundreds of millions of cases of the diarrheal disease shigellosis per year worldwide. Shigella is acquired by ingestion of contaminated food or water; upon reaching the colon, the bacteria invade colonic epithelial cells, replicate intracellularly, spread to adjacent cells, and provoke an intense inflammatory response. There is no animal model that faithfully recapitulates human disease; thus, cultured cells have been used to model Shigella pathogenesis. However, the use of transformed cells in culture does not provide the same environment to the bacteria as the normal human intestinal epithelium. Recent advances in tissue culture now enable the cultivation of human intestinal enteroids (HIEs), which are derived from human intestinal stem cells, grown ex vivo, and then differentiated into "mini-intestines." Here, we demonstrate that HIEs can be used to model Shigella pathogenesis. We show that Shigella flexneri invades polarized HIE monolayers preferentially via the basolateral surface. After S. flexneri invades HIE monolayers, S. flexneri replicates within HIE cells and forms actin tails. S. flexneri also increases the expression of HIE proinflammatory signals and the amino acid transporter SLC7A5. Finally, we demonstrate that disruption of HIE tight junctions enables S. flexneri invasion via the apical surface.
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11
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Günther J, Seyfert HM. The first line of defence: insights into mechanisms and relevance of phagocytosis in epithelial cells. Semin Immunopathol 2018; 40:555-565. [PMID: 30182191 PMCID: PMC6223882 DOI: 10.1007/s00281-018-0701-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 08/09/2018] [Indexed: 12/16/2022]
Abstract
Epithelial tissues cover most of the external and internal surfaces of the body and its organs. Inevitably, these tissues serve as first line of defence against inorganic, organic, and microbial intruders. Epithelial cells are the main cell type of these tissues. Besides their function as cellular barrier, there is growing evidence that epithelial cells are of particular relevance as initial sensors of danger and also as executers of adequate defence responses. These cells feature various essential functions to maintain tissue integrity in health and disease. In this review, we survey some of the different innate immune functions of epithelial cells in mucosal tissues being constantly exposed to a plethora of harmless contaminants but also of pathogens. We discuss how epithelial cells avoid inadequate immune responses in such conditions. In particular, we will focus on the diverse types and mechanisms of phagocytosis used by epithelial cells to not only maintain homeostasis but to also harness the host response against invading pathogens.
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Affiliation(s)
- Juliane Günther
- Institute for Genome Biology, Leibniz Institute for Farm Animal Biology, 18196, Dummerstorf, Germany.
| | - Hans-Martin Seyfert
- Institute for Genome Biology, Leibniz Institute for Farm Animal Biology, 18196, Dummerstorf, Germany
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12
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Intracellular Staphylococcus aureus Modulates Host Central Carbon Metabolism To Activate Autophagy. mSphere 2018; 3:3/4/e00374-18. [PMID: 30089650 PMCID: PMC6083095 DOI: 10.1128/msphere.00374-18] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Staphylococcus aureus is a facultative intracellular pathogen that invades and replicates within many types of phagocytic and nonphagocytic cells. During intracellular infection, S. aureus is capable of subverting xenophagy and escaping to the cytosol of the host cell. Furthermore, drug-induced autophagy facilitates the intracellular replication of S. aureus, but the reasons behind this are unclear. Here, we have studied the host central carbon metabolism during S. aureus intracellular infection. We found extensive metabolic rerouting and detected several distinct metabolic changes that suggested starvation-induced autophagic flux in infected cells. These changes included increased uptake but lower intracellular levels of glucose and low abundance of several essential amino acids, as well as markedly upregulated glutaminolysis. Furthermore, we show that AMP-activated protein kinase (AMPK) and extracellular signal-regulated kinase (ERK) phosphorylation levels are significantly increased in infected cells. Interestingly, while autophagy was activated in response to S. aureus invasion, most of the autophagosomes detected in infected cells did not contain bacteria, suggesting that S. aureus induces the autophagic flux during cell invasion for energy generation and nutrient scavenging. Accordingly, AMPK inhibition halted S. aureus intracellular proliferation.IMPORTANCEStaphylococcus aureus escapes from immune recognition by invading a wide range of human cells. Once the pathogen becomes intracellular, the most important last resort antibiotics are not effective. Therefore, novel anti-infective therapies against intracellular S. aureus are urgently needed. Here, we have studied the physiological changes induced in the host cells by S. aureus during its intracellular proliferation. This is important, because the pathogen exploits the host cell's metabolism for its own proliferation. We find that S. aureus severely depletes glucose and amino acid pools, which leads to increased breakdown of glutamine by the host cell in an attempt to meet its own metabolic needs. All of these metabolic changes activate autophagy in the host cell for nutrient scavenging and energy generation. The metabolic activation of autophagy could be used by the pathogen to sustain its own intracellular survival, making it an attractive target for novel anti-infectives.
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13
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Abstract
Shigella is a leading cause of dysentery worldwide, responsible for up to 165 million cases of shigellosis each year. Shigella is also recognised as an exceptional model pathogen to study key issues in cell biology and innate immunity. Several infection models have been useful to explore Shigella biology; however, we still lack information regarding the events taking place during the Shigella infection process in vivo Here, we discuss a selection of mechanistic insights recently gained from studying Shigella infection of zebrafish (Danio rerio), with a focus on cytoskeleton rearrangements and cellular immunity. We also discuss how infection of zebrafish can be used to investigate new concepts underlying infection control, including emergency granulopoiesis and the use of predatory bacteria to combat antimicrobial resistance. Collectively, these insights illustrate how Shigella infection of zebrafish can provide fundamental advances in our understanding of bacterial pathogenesis and vertebrate host defence. This information should also provide vital clues for the discovery of new therapeutic strategies against infectious disease in humans.
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Affiliation(s)
- Gina M Duggan
- Section of Microbiology, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Serge Mostowy
- Section of Microbiology, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
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