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Anne-Laure Roux, Albertus Viljoen, Aïcha Bah, Roxane Simeone, Audrey Bernut, Laura Laencina, Therese Deramaudt, Martin Rottman, Jean-Louis Gaillard, Laleh Majlessi, Roland Brosch, Fabienne Girard-Misguich, Isabelle Vergne, Chantal de Chastellier, Laurent Kremer, Jean-Louis Herrmann
Mycobacterium abscessus is a pathogenic, rapidly growing mycobacterium responsible for pulmonary and cutaneous infections in immunocompetent patients and in patients with Mendelian disorders, such as cystic fibrosis (CF). Mycobacterium abscessus is known to transition from a smooth (S) morphotype with cell surface-associated glycopeptidolipids (GPL) to a rough (R) morphotype lacking GPL. Herein, we show that M. abscessus S and R variants are able to grow inside macrophages and are present in morphologically distinct phagosomes...
November 2016: Open Biology
Tariq Hussain, Syed Zahid Ali Shah, Deming Zhao, Srinand Sreevatsan, Xiangmei Zhou
Mycobacterium avium subsp. paratuberculosis (MAP) is an intracellular pathogen and is the causative agent of Johne's disease of domestic and wild ruminants. Johne's disease is characterized by chronic granulomatous enteritis leading to substantial economic losses to the livestock sector across the world. MAP persistently survives in phagocytic cells, most commonly in macrophages by disrupting its early antibacterial activity. MAP triggers several signaling pathways after attachment to pathogen recognition receptors (PRRs) of phagocytic cells...
December 1, 2016: Cell Communication and Signaling: CCS
Kristopher Jl Irizarry, Adam Chan, Derek Kettle, Steven Kezian, Dominic Ma, Louis Palacios, Qingshun Li, Calvin L Keeler, Yvonne Drechsler
The goal of this project was to characterize the molecular and cellular roles of various gene targets regulated by 8 miRNAs in differentiating macrophages. Among a number of miRNAs that are found to be expressed in avian macrophages, we focused on eight specific miRNAs (miR-1618, miR-1586, miR-1633, miR-1627, miR-1646, miR-1649, miR-1610, miR-1647) associated with macrophage activation through Wnt signaling, ubiquitination, PPAR mediated macrophage function, vesicle mediated cytokine trafficking, and WD40 domain proteins in macrophage differentiation...
November 29, 2016: MicroRNA
Katerina S Jurkoshek, Ying Wang, Jaffre J Athman, Marian R Barton, Pamela A Wearsch
The production of extracellular vesicles is a universal mechanism for intercellular communication that is conserved across kingdoms. Prokaryotes secrete 50-250 nm membrane vesicles (MVs) in a manner that is regulated by environmental stress and is thought to promote survival. Since many types of host-derived stress are encountered during infection, this implies an important role for MV secretion in bacterial pathogenesis. Accordingly, MVs produced by gram-positive and gram-negative pathogens contain toxins, virulence factors, and other molecules that promote survival in the host...
2016: Frontiers in Cell and Developmental Biology
Bowen Liu, Zihao Teng, Jianfeng Wang, Gejin Lu, Xuming Deng, Li Li
The foodborne pathogenic bacterial species Listeria monocytogenes (L. monocytogenes) has caused incalculable damages to public health, and its successful infection requires various virulence factors, including Listeriolysin O (LLO). By forming pores in phagosomal membranes and even in some organelles, LLO plays an indispensable role in the ability of L. monocytogenes to escape from host immune attacks. Because of its critical role, LLO offers an appropriate therapeutic target against L. monocytogenes infection...
November 22, 2016: Fitoterapia
Zan Li, Shi-Hai Yan, Chen Chen, Zhi-Rong Geng, Jia-Yin Chang, Chun-Xia Chen, Bing-Huan Huang, Zhi-Lin Wang
Reactions of peroxynitrite (ONOO(-)) with biomolecules can lead to cytotoxic and cytoprotective events. Due to the difficulty of directly and unambiguously measuring its levels, most of the beneficial effects associated with ONOO(-) in vivo remain controversial or poorly characterized. Recently, optical imaging has served as a powerful noninvasive approach to studying ONOO(-) in living systems. However, ratiometric probes for ONOO(-) are currently lacking. Herein, we report the design, synthesis, and biological evaluation of F482, a novel fluorescence indicator that relies on ONOO(-)-induced diene oxidation...
November 15, 2016: Biosensors & Bioelectronics
Andreas Westphal, Weijia Cheng, Jinbo Yu, Guntram Grassl, Martina Krautkrämer, Otto Holst, Niko Föger, Kyeong-Hee Lee
Subcellular compartmentalization of receptor signaling is an emerging principle in innate immunity. However, the functional integration of receptor signaling pathways into membrane trafficking routes and its physiological relevance for immune responses is still largely unclear. In this study, using Lyst-mutant beige mice, we show that lysosomal trafficking regulator Lyst links endolysosomal organization to the selective control of toll-like receptor 3 (TLR3)- and TLR4-mediated proinflammatory responses. Consequently, Lyst-mutant mice showed increased susceptibility to bacterial infection and were largely resistant to endotoxin-induced septic shock...
November 23, 2016: Journal of Experimental Medicine
Mahaveer Singh, Hemant Jadhav, Tanya B
Dynamin is a GTPase, which plays a vital role in clathrin dependent endocytosis and other vesicular trafficking processes. Dynamin acts as scissor with debatable mechanism for newly formed vesicles originating from plasma membrane. Dynamin related proteins are important components in scission of various organelles such as clathrin coated vesicles, phagosomes and mitochondria, etc. helping in organelle division, viral resistance and mitochondrial fusion/division. Dysfunction and mutations in dynamin have been implicated in various disorders, where endocytic trafficking is involved, such as Alzheimer's, Parkinson's, Huntington's, Charcot-Marie Tooth disease, Heart failure, Schizophrenia, Epilepsy, Cancer, Optic atrophy, Down syndrome, Osteoporosis etc...
November 22, 2016: Molecular Pharmacology
Slavena Vylkova, Michael C Lorenz
The interaction of Candida albicans with the innate immune system is the key determinant of the pathogen/commensal balance and has selected for adaptations that facilitate the utilization of nutrients commonly found within the host, including proteins and amino acids; many of the catabolic pathways needed to assimilate these compounds are required for persistence in the host. We have shown that C. albicans co-opts amino acid catabolism to generate and excrete ammonia, which raises extracellular pH, both in vitro and in vivo and induces hyphal morphogenesis...
November 21, 2016: Infection and Immunity
Jane Atesoh Awuh, Trude Helen Flo
Macrophages play an essential role in the immune system by ingesting and degrading invading pathogens, initiating an inflammatory response and instructing adaptive immune cells, and resolving inflammation to restore homeostasis. More interesting is the fact that some bacteria have evolved to use macrophages as a natural habitat and tools of spread in the host, e.g., Mycobacterium tuberculosis (Mtb) and some non-tuberculous mycobacteria (NTM). Mtb is considered one of humanity's most successful pathogens and is the causal agent of tuberculosis, while NTMs cause opportunistic infections all of which are of significant public health concern...
November 19, 2016: Cellular and Molecular Life Sciences: CMLS
Ignacio Cebrian, Cristina Croce, Néstor A Guerrero, Nicolas Blanchard, Luis S Mayorga
Cross-presentation by MHC class I molecules allows the detection of exogenous antigens by CD8(+) T lymphocytes. This process is crucial to initiate cytotoxic immune responses against many pathogens (i.e., Toxoplasma gondii) and tumors. To achieve efficient cross-presentation, dendritic cells (DCs) have specialized endocytic pathways; however, the molecular effectors involved are poorly understood. In this work, we identify the small GTPase Rab22a as a key regulator of MHC-I trafficking and antigen cross-presentation by DCs...
December 2016: EMBO Reports
Yumiko Tsukamoto, Yumi Maeda, Toshiki Tamura, Tetsu Mukai, Satoshi Mitarai, Saburo Yamamoto, Masahiko Makino
Enhancement of the T cell-stimulating ability of Mycobacterium bovis BCG (BCG) is necessary to develop an effective tuberculosis vaccine. For this purpose, we introduced the PEST-HSP70-major membrane protein-II (MMPII)-PEST fusion gene into ureC-gene depleted recombinant (r) BCG to produce BCG-PEST. The PEST sequence is involved in the proteasomal processing of antigens. BCG-PEST secreted the PEST-HSP70-MMPII-PEST fusion protein and more efficiently activated human monocyte-derived dendritic cells (DCs) in terms of phenotypic changes and cytokine productions than an empty-vector-introduced BCG or HSP70-MMPII gene-introduced ureC gene-depleted BCG (BCG-DHTM)...
December 7, 2016: Vaccine
Jeanette E Bröms, Lena Meyer, Anders Sjöstedt
The Gram-negative bacterium Francisella tularensis is the etiological agent of the zoonotic disease tularemia. Its life cycle is characterized by an ability to survive within phagocytic cells through phagosomal escape and replication in the cytosol, ultimately causing inflammasome activation and host cell death. Required for these processes is the Francisella pathogenicity island (FPI), which encodes a Type VI secretion system (T6SS) that is active during intracellular infection. In this study, we analyzed the role of the FPI-component IglE, a lipoprotein which we previously have shown to be secreted in a T6SS-dependent manner...
November 10, 2016: Virulence
Jessica J Chinison, Lia Danelishvili, Rashmi Gupta, Sasha J Rose, Lmar M Babrak, Luiz E Bermudez
BACKGROUND: Mycobacterium avium subsp. hominissuis is a common intracellular pathogen that infects patients with HIV/AIDS and cause lung infection in patients with underlying lung pathology. M.avium preferably infects macrophages and uses diverse mechanisms to alter phagosome maturation. Once in the macrophage, the pathogen can alter the host cellular defenses by secreting proteins into the cytosol of host cells, but despite considerable research, only a few secreted effector proteins have been identified...
November 9, 2016: BMC Microbiology
Robert J Evans, Kerstin Voelz, Simon A Johnston, Robin C May
Flow cytometry is a powerful analytical technique, which is increasingly being used to study the interaction between host cells and intracellular pathogens. Flow cytometry is capable of measuring a greater number of infected cells within a sample compared to alternative techniques such as fluorescence microscopy. This means that robust quantification of rare events during infection is possible. Our lab and others have developed flow cytometry methods to study interactions between host cells and intracellular pathogens, such as Cryptococcus neoformans, to quantify phagocytosis, intracellular replication, and non-lytic expulsion or "vomocytosis" from the phagosome...
2017: Methods in Molecular Biology
Shumin Tan, Robin M Yates, David G Russell
Macrophages fulfill most of their microbicidal duties in their phagosomes following uptake of microbes. However, some microbes, such as Mycobacterium tuberculosis, have evolved mechanisms to subvert the normal maturation process of their phagocytic compartment to limit the hostility of this environment. The experimental analysis of this process and its subsequent impact on bacterial fitness is technically demanding and has required the development of a broad range of readouts to correlate function and outcome...
2017: Methods in Molecular Biology
Akriti Prashar, Sana I S Khan, Mauricio R Terebiznik
Filamentous targets are internalized via phagocytic cups that last for several minutes before closing to form a phagosome. This characteristic offers the possibility to study key events in phagocytosis with greater spatial and temporal resolution than is possible to achieve using spherical particles, for which the transition from a phagocytic cup to an enclosed phagosome occurs within a few seconds after particle attachment. In this chapter, we provide methodologies to prepare filamentous bacteria and describe how they can be used as targets to study different aspects of phagocytosis...
2017: Methods in Molecular Biology
Shiya Cheng, Kai Liu, Chonglin Yang, Xiaochen Wang
The unique features of programmed cell death during C. elegans development provide an outstanding system to decipher the mechanisms governing phagocytic removal of apoptotic cells. Like in many other organisms, phagocytosis in C. elegans involves several essential events, including exposure of eat-me signals on the cell corpse surface, cell corpse recognition and engulfment by phagocytes, and maturation of phagosomes for cell corpse destruction. Forward or reverse genetic approaches, microscopy-based cell biological methods, and biochemical assays have successfully been employed to identify key factors that control different steps of phagocytosis and to understand their functions in these cellular events...
2017: Methods in Molecular Biology
Julien Peltier, Anetta Härtlova, Matthias Trost
Phagocytosis is the process that engulfs particles in vesicles called phagosomes that are trafficked through a series of maturation steps, culminating in the destruction of the internalized cargo. Because phagosomes are in direct contact with the particle and undergo constant fusion and fission events with other organelles, characterization of the phagosomal proteome is a powerful tool to understand mechanisms controlling innate immunity as well as vesicle trafficking. The ability to isolate highly pure phagosomes through the use of latex beads led to an extensive use of proteomics to study phagosomes under different stimuli...
2017: Methods in Molecular Biology
Anetta Härtlova, Julien Peltier, Orsolya Bilkei-Gorzo, Matthias Trost
Phagocytosis plays an essential role in the immune system for the defense against invading microorganisms and the clearing of apoptotic cells. After internalization, the newly formed phagosome is constantly remodeled by fusion with early endosomes, late endosomes, and lysosomes. These changes ultimately deliver the engulfed material into the terminal degradative compartments known as phagolysosomes. However, defective phagosome maturation can result in inflammatory or autoimmune disease depending on the type of phagosome cargo...
2017: Methods in Molecular Biology
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