scholarly journals The BaramicinA gene is required at several steps of the host defense against Enterococcus faecalis and Metarhizium robertsii in a septic wound infection model in Drosophila melanogaster

2020 ◽  
Author(s):  
Jianqiong Huang ◽  
Yanyan Lou ◽  
Jiyong Liu ◽  
Philippe Bulet ◽  
Renjie Jiao ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Host Defense ◽  
Fungal Infections ◽  
Sequence Similarity ◽  
Infection Model ◽  
Toll Pathway ◽  
Phenotypic Analysis ◽  
Gram Positive ◽  
Furin Cleavage ◽  
Metarhizium Robertsii

AbstractThe host defense against several Gram-positive bacterial and fungal infections is mostly mediated by the Toll pathway in Drosophila, which regulates the expression of multiple genes including effectors of the innate immune response. One such potential effector is IMPPP/BaraA, a precursor protein that is processed at furin cleavage sites into an armamentarium of small DIM peptides that display a high degree of sequence similarity. We report here the generation of multiple mutants affecting this gene. Our phenotypic analysis revealed a specific sensitivity to pathogens belonging to distinct kingdoms, the Gram-positive bacterium Enterococcus faecalis and the entomopathogenic fungus Metarhizium anisopliae, only in septic injury models of infection. Unexpectedly, we failed to reveal a consistently increased microbial burden in the mutant flies infected with either of these microorganisms, opening the possibility for a role of BaraA in resilience rather than in resistance, which we were however unable to confirm. We also found that some BaraA-derived DIM peptides display an antimicrobial activity at millimolar concentrations in vitro. BaraA is additionally required for an efficient cleavage of pro-phenol oxidase into an active enzyme. BaraA is also involved in the cellular host defense, but through distinct mechanisms: it needs to be expressed in hemocytes for an efficient response solely to E. faecalis infection whereas it is required for the uptake by plasmatocytes of M. robertsii conidia. We propose a model whereby BaraA secreted by hemocytes may act at a very short range and protect host tissues or organs targeted specifically by E. faecalis. This study thus reveals an unexpected functional complexity of a potential effector of the Toll pathway in the host defense against specific infections.

scholarly journals Differential Requirements for Mediator Complex Subunits in Drosophila melanogaster Host Defense Against Fungal and Bacterial Pathogens

2021 ◽  
Vol 11 ◽  
Author(s):  
Chuqin Huang ◽  
Rui Xu ◽  
Samuel Liégeois ◽  
Di Chen ◽  
Zi Li ◽  
...  
Keyword(s):  
Immune Response ◽  
Host Defense ◽  
Bacterial Infections ◽  
Fungal Infections ◽  
Transcriptional Response ◽  
Erwinia Carotovora ◽  
Mediator Complex ◽  
Toll Pathway ◽  
Metarhizium Robertsii ◽  
Immune Factor

The humoral immune response to bacterial or fungal infections in Drosophila relies largely on a transcriptional response mediated by the Toll and Immune deficiency NF-κB pathways. Antimicrobial peptides are potent effectors of these pathways and allow the organism to attack invading pathogens. Dorsal-related Immune Factor (DIF), a transcription factor regulated by the Toll pathway, is required in the host defense against fungal and some Gram-positive bacterial infections. The Mediator complex is involved in the initiation of transcription of most RNA polymerase B (PolB)-dependent genes by forming a functional bridge between transcription factors bound to enhancer regions and the gene promoter region and then recruiting the PolB pre-initiation complex. Mediator is formed by several modules that each comprises several subunits. The Med17 subunit of the head module of Mediator has been shown to be required for the expression of Drosomycin, which encodes a potent antifungal peptide, by binding to DIF. Thus, Mediator is expected to mediate the host defense against pathogens controlled by the Toll pathway-dependent innate immune response. Here, we first focus on the Med31 subunit of the middle module of Mediator and find that it is required in host defense against Aspergillus fumigatus, Enterococcus faecalis, and injected but not topically-applied Metarhizium robertsii. Thus, host defense against M. robertsii requires Dif but not necessarily Med31 in the two distinct infection models. The induction of some Toll-pathway-dependent genes is decreased after a challenge of Med31 RNAi-silenced flies with either A. fumigatus or E. faecalis, while these flies exhibit normal phagocytosis and melanization. We have further tested most Mediator subunits using RNAi by monitoring their survival after challenges to several other microbial infections known to be fought off through DIF. We report that the host defense against specific pathogens involves a distinct set of Mediator subunits with only one subunit for C. glabrata or Erwinia carotovora carotovora, at least one for M. robertsii or a somewhat extended repertoire for A. fumigatus (at least eight subunits) and E. faecalis (eight subunits), with two subunits, Med6 and Med11 being required only against A. fumigatus. Med31 but not Med17 is required in fighting off injected M. robertsii conidia. Thus, the involvement of Mediator in Drosophila innate immunity is more complex than expected.

scholarly journals Reinforcing the Immunocompromised Host Defense against Fungi: Progress beyond the Current State of the Art

2021 ◽  
Vol 7 (6) ◽  
pp. 451
Author(s):  
Georgios Karavalakis ◽  
Evangelia Yannaki ◽  
Anastasia Papadopoulou
Keyword(s):  
Host Defense ◽  
Hematopoietic Cell Transplantation ◽  
State Of The Art ◽  
Fungal Infections ◽  
Solid Organ Transplantation ◽  
Immunocompromised Host ◽  
Antifungal Drugs ◽  
Solid Organ ◽  
Cell Immunotherapy ◽  
Life Threatening

Despite the availability of a variety of antifungal drugs, opportunistic fungal infections still remain life-threatening for immunocompromised patients, such as those undergoing allogeneic hematopoietic cell transplantation or solid organ transplantation. Suboptimal efficacy, toxicity, development of resistant variants and recurrent episodes are limitations associated with current antifungal drug therapy. Adjunctive immunotherapies reinforcing the host defense against fungi and aiding in clearance of opportunistic pathogens are continuously gaining ground in this battle. Here, we review alternative approaches for the management of fungal infections going beyond the state of the art and placing an emphasis on fungus-specific T cell immunotherapy. Harnessing the power of T cells in the form of adoptive immunotherapy represents the strenuous protagonist of the current immunotherapeutic approaches towards combating invasive fungal infections. The progress that has been made over the last years in this field and remaining challenges as well, will be discussed.

scholarly journals Pharmacodynamics of Daptomycin against Enterococcus faecium and Enterococcus faecalis in the Murine Thigh Infection Model

2018 ◽  
Vol 62 (10) ◽  
Author(s):  
James M. Kidd ◽  
Kamilia Abdelraouf ◽  
Tomefa E. Asempa ◽  
Romney M. Humphries ◽  
David P. Nicolau
Keyword(s):  
Enterococcus Faecalis ◽  
Enterococcus Faecium ◽  
Hill Equation ◽  
Infection Model ◽  
Free Drug Concentration ◽  
Time Curve ◽  
Content Type ◽  
Concentration Time ◽  
The Hill ◽  
Susceptibility Breakpoint

ABSTRACT The Clinical and Laboratory Standards Institute (CLSI) daptomycin MIC susceptibility breakpoint for the treatment of enterococcal infections is ≤4 μg/ml. However, patients receiving daptomycin for the treatment of infections caused by enterococci with MICs of ≤4 μg/ml may experience treatment failures. We assessed the pharmacodynamics of daptomycin against enterococci in a neutropenic murine thigh infection model and determined the exposures necessary for bacteriostasis and a 1-log10-CFU reduction of Enterococcus faecalis and Enterococcus faecium. We further characterized daptomycin efficacy at clinically achievable exposures. Six E. faecium and 6 E. faecalis isolates (daptomycin MICs, 0.5 to 32 μg/ml) were studied. Daptomycin was administered at various doses over 24 h to achieve area under the free drug concentration-time curve-to-MIC ratios (fAUC0–24/MIC) ranging from 1 to 148. Daptomycin regimens that simulate mean human exposures following doses of 6, 8, and 10 mg/kg of body weight/day were also studied. Efficacy was assessed by the differences in the number of log10 CFU per thigh at 24 h. The Hill equation was used to estimate the fAUC0–24/MIC required to achieve bacteriostasis and a 1-log10-CFU reduction. For E. faecium, a 1-log10-CFU reduction required an fAUC0–24/MIC of 12.9 (R2 = 0.71). For E. faecalis, a 1-log10-CFU reduction was not achieved, while the fAUC0–24/MIC required for stasis was 7.2 (R2 = 0.8). With a human-simulated regimen of 6 mg/kg/day, a 1-log10-CFU reduction was observed in 3/3 E. faecium isolates with MICs of <4 μg/ml and 0/3 E. faecium isolates with MICs of ≥4 μg/ml; however, a 1-log10-CFU reduction was not achieved for any of the 6 E. faecalis isolates. These results, alongside clinical data, prompt a reevaluation of the current breakpoint.

scholarly journals In VivoEfficacy of Anuran Trypsin Inhibitory Peptides against Staphylococcal Skin Infection and the Impact of Peptide Cyclization

2015 ◽  
Vol 59 (4) ◽  
pp. 2113-2121 ◽  
Author(s):  
U. Malik ◽  
O. N. Silva ◽  
I. C. M. Fensterseifer ◽  
L. Y. Chan ◽  
R. J. Clark ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Cyclic Peptide ◽  
Sequence Similarity ◽  
Infection Model ◽  
Content Type ◽  
Wide Range ◽  
Inhibitory Activities ◽  
The Impact

ABSTRACTStaphylococcus aureusis a virulent pathogen that is responsible for a wide range of superficial and invasive infections. Its resistance to existing antimicrobial drugs is a global problem, and the development of novel antimicrobial agents is crucial. Antimicrobial peptides from natural resources offer potential as new treatments against staphylococcal infections. In the current study, we have examined the antimicrobial properties of peptides isolated from anuran skin secretions and cyclized synthetic analogues of these peptides. The structures of the peptides were elucidated by nuclear magnetic resonance (NMR) spectroscopy, revealing high structural and sequence similarity with each other and with sunflower trypsin inhibitor 1 (SFTI-1). SFTI-1 is an ultrastable cyclic peptide isolated from sunflower seeds that has subnanomolar trypsin inhibitory activity, and this scaffold offers pharmaceutically relevant characteristics. The five anuran peptides were nonhemolytic and noncytotoxic and had trypsin inhibitory activities similar to that of SFTI-1. They demonstrated weakin vitroinhibitory activities againstS. aureus, but several had strong antibacterial activities againstS. aureusin anin vivomurine wound infection model. pYR, an immunomodulatory peptide fromRana sevosa, was the most potent, with complete bacterial clearance at 3 mg · kg−1. Cyclization of the peptides improved their stability but was associated with a concomitant decrease in antimicrobial activity. In summary, these anuran peptides are promising as novel therapeutic agents for treating infections from a clinically resistant pathogen.

Topics in Chronic Granulomatous Disease

PEDIATRICS ◽  
1991 ◽  
Vol 88 (1) ◽  
pp. 183-185
Author(s):  
SHIGENOBU UMEKI
Keyword(s):  
Nadph Oxidase ◽  
Chronic Granulomatous Disease ◽  
Host Defense ◽  
Superoxide Anion ◽  
Fungal Infections ◽  
Regulatory Elements ◽  
Granulomatous Disease ◽  
Phagocytic Cells ◽  
Oxidase System ◽  
Membrane Bound

To the Editor.— Such phagocytic cells as neutrophils and macrophages are crucial elements in the host defense against bacterial [See table in the PDF file] and fungal infections. Microbicidal activity depends to a large extent on NADPH oxidase system, which can be activated by stimuli (bacteria, fungi) and which generates the superoxide anion and other highly reactive forms of reduced oxygen.1,2 The neutrophil NADPH oxidase system is composed functionally of membrane-bound catalytic components (which consist of at least two constituents, the low potential cytochrome b5583-5 and flavoprotein5) and soluble cytosolic components6,7 which participate as either catalytic or regulatory elements.

scholarly journals Effects of copper nanoparticle exposure on host defense in a murine pulmonary infection model

2011 ◽  
Vol 8 (1) ◽  
pp. 29 ◽  
Author(s):  
Jong Sung Kim ◽  
Andrea Adamcakova-Dodd ◽  
Patrick T O'Shaughnessy ◽  
Vicki H Grassian ◽  
Peter S Thorne
Keyword(s):  
Host Defense ◽  
Pulmonary Infection ◽  
Infection Model ◽  
Copper Nanoparticle ◽  
Nanoparticle Exposure

scholarly journals Do Mast Cells Contribute to the Antifungal Host Defense?

Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2510
Author(s):  
Paulina Żelechowska ◽  
Joanna Pastwińska ◽  
Ewa Brzezińska-Błaszczyk ◽  
Justyna Agier
Keyword(s):  
Mast Cells ◽  
Host Defense ◽  
Immune Cells ◽  
Defense Mechanisms ◽  
Fungal Infections ◽  
Current Knowledge ◽  
Extracellular Dna ◽  
Opportunistic Pathogens ◽  
Strategic Location ◽  
Fungal Kingdom

The fungal kingdom includes a group of microorganisms that are widely distributed in the environment, and therefore the exposure to them is almost constant. Furthermore, fungal components of the microbiome, i.e., mycobiome, could serve as a reservoir of potentially opportunistic pathogens. Despite close encounters with fungi, defense mechanisms that develop during fungal infections remain unexplored. The strategic location of mast cells (MCs) close to the external environment places them among the first cells to encounter pathogens along with the other innate immune cells. MCs are directly involved in the host defense through the ability to destroy pathogens or indirectly by activating other immune cells. Most available data present MCs’ involvement in antibacterial, antiviral, or antiparasitic defense mechanisms. However, less is known about their contribution in defense mechanisms against fungi. MCs may support immune responses to fungi or their specific molecules through initiated degranulation, synthesis and release of cytokines, chemokines, mediators, and generation of reactive oxygen species (ROS), as well as immune cells’ recruitment, phagocytosis, or provision of extracellular DNA traps. This review summarizes current knowledge on host defense mechanisms against fungi and MCs’ involvement in those processes. It also describes the effects of fungi or fungus-derived constituents on MCs’ activity.

scholarly journals A Type IV-Secretion-Like System Is Required for Conjugative DNA Transport of Broad-Host-Range Plasmid pIP501 in Gram-Positive Bacteria

2007 ◽  
Vol 189 (6) ◽  
pp. 2487-2496 ◽  
Author(s):  
Mohammad Y. Abajy ◽  
Jolanta Kopeć ◽  
Katarzyna Schiwon ◽  
Michal Burzynski ◽  
Mike Döring ◽  
...  
Keyword(s):  
Host Range ◽  
Sequence Similarity ◽  
Type Iv Secretion ◽  
Conjugative Plasmid ◽  
Computer Assisted ◽  
Transcriptional Level ◽  
Broad Host Range ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Type Iv

ABSTRACT Plasmid pIP501 has a very broad host range for conjugative transfer among a wide variety of gram-positive bacteria and gram-negative Escherichia coli. Functionality of the pIP501 transfer (tra) genes in E. coli was proven by pIP501 retrotransfer to Enterococcus faecalis (B. Kurenbach, C. Bohn, J. Prabhu, M. Abudukerim, U. Szewzyk, and E. Grohmann, Plasmid 50:86-93, 2003). The 15 pIP501 tra genes are organized in a single operon (B. Kurenbach, J. Kopeć, M. Mägdefrau, K. Andreas, W. Keller, C. Bohn, M. Y. Abajy, and E. Grohmann, Microbiology 152:637-645, 2006). The pIP501 tra operon is negatively autoregulated at the transcriptional level by the conjugative DNA relaxase TraA. Three of the 15 pIP501-encoded Tra proteins show significant sequence similarity to the Agrobacterium type IV secretion system proteins VirB1, VirB4, and VirD4. Here we report a comprehensive protein-protein interaction map of all of the pIP501-encoded Tra proteins determined by the yeast two-hybrid assay. Most of the interactions were verified in vitro by isolation of the protein complexes with pull-down assays. In conjunction with known or postulated functions of the pIP501-encoded Tra proteins and computer-assisted prediction of their cellular location, we propose a model for the first type IV-secretion-like system encoded by a conjugative plasmid from gram-positive bacteria.

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