scholarly journals Verloren negatively regulates the expression of IMD pathway dependent antimicrobial peptides in Drosophila

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pragya Prakash ◽  
Arghyashree Roychowdhury-Sinha ◽  
Akira Goto
Keyword(s):  
Antimicrobial Peptides ◽  
Bacterial Load ◽  
Tumor Necrosis Factor Receptor ◽  
Constitutive Expression ◽  
Human Tumor ◽  
Negative Regulator ◽  
Gram Negative ◽  
Knock Down ◽  
Imd Pathway

AbstractDrosophila immune deficiency (IMD) pathway is similar to the human tumor necrosis factor receptor (TNFR) signaling pathway and is preferentially activated by Gram-negative bacterial infection. Recent studies highlighted the importance of IMD pathway regulation as it is tightly controlled by numbers of negative regulators at multiple levels. Here, we report a new negative regulator of the IMD pathway, Verloren (Velo). Silencing of Velo led to constitutive expression of the IMD pathway dependent antimicrobial peptides (AMPs), and Escherichia coli stimulation further enhanced the AMP expression. Epistatic analysis indicated that Velo knock-down mediated AMP upregulation is dependent on the canonical members of the IMD pathway. The immune fluorescent study using overexpression constructs revealed that Velo resides both in the nucleus and cytoplasm, but the majority (~ 75%) is localized in the nucleus. We also observed from in vivo analysis that Velo knock-down flies exhibit significant upregulation of the AMP expression and reduced bacterial load. Survival experiments showed that Velo knock-down flies have a short lifespan and are susceptible to the infection of pathogenic Gram-negative bacteria, P. aeruginosa. Taken together, these data suggest that Velo is an additional new negative regulator of the IMD pathway, possibly acting in both the nucleus and cytoplasm.

scholarly journals Tissue-Specific Regulation of Drosophila NF-κB Pathway Activation by Peptidoglycan Recognition Protein SC

2015 ◽  
Vol 8 (1) ◽  
pp. 67-80 ◽  
Author(s):  
Denis Costechareyre ◽  
Florence Capo ◽  
Alexandre Fabre ◽  
Delphine Chaduli ◽  
Christine Kellenberger ◽  
...  
Keyword(s):  
Fat Body ◽  
Bacterial Load ◽  
Negative Regulator ◽  
Loss Of Function ◽  
Peptidoglycan Recognition Protein ◽  
Imd Pathway ◽  
Pathway Activation ◽  
Recognition Protein ◽  
Specific Regulation

In Drosophila, peptidoglycan (PGN) is detected by PGN recognition proteins (PGRPs) that act as pattern recognition receptors. Some PGRPs such as PGRP-LB or PGRP-SCs are able to cleave PGN, therefore reducing the amount of immune elicitors and dampening immune deficiency (IMD) pathway activation. The precise role of PGRP-SC is less well defined because the PGRP-SC genes (PGRP-SC1a, PGRP-SC1b and PGRP-SC2) lie very close on the chromosome and have been studied using a deletion encompassing the three genes. By generating PGRP-SC-specific mutants, we reevaluated the roles of PGRP-LB, PGRP-SC1 and PGRP-SC2, respectively, during immune responses. We showed that these genes are expressed in different gut domains and that they follow distinct transcriptional regulation. Loss-of-function mutant analysis indicates that PGRP-LB is playing a major role in IMD pathway activation and bacterial load regulation in the gut, although PGRP-SCs are expressed at high levels in this organ. We also demonstrated that PGRP-SC2 is the main negative regulator of IMD pathway activation in the fat body. Accordingly, we showed that mutants for either PGRP-LB or PGRP-SC2 displayed a distinct susceptibility to bacteria depending on the infection route. Lastly, we demonstrated that PGRP-SC1 and PGRP-SC2 are required in vivo for full Toll pathway activation by Gram-positive bacteria.

scholarly journals Aedes aegypti (Diptera: Culicidae) Immune Responses with Different Feeding Regimes Following Infection by the Entomopathogenic Fungus Metarhizium anisopliae

Insects ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 95 ◽  
Author(s):  
Sara Cabral ◽  
Adriano de Paula ◽  
Richard Samuels ◽  
Rodrigo da Fonseca ◽  
Simone Gomes ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Immune Responses ◽  
Antimicrobial Peptides ◽  
Fungal Infection ◽  
Fat Body ◽  
Negative Regulator ◽  
Toll Pathway ◽  
Promising Alternative ◽  
Imd Pathway ◽  
Feeding Regimes

The mosquito Aedes aegypti is the most notorious vector of illness-causing viruses. The use of entomopathogenic fungi as bioinsecticides is a promising alternative for the development of novel mosquito control strategies. We investigate whether differences in immune responses could be responsible for modifications in survival rates of insects following different feeding regimes. Sucrose and blood-fed adult A. aegypti females were sprayed with M. anisopliae 1 × 106 conidia mL−1, and after 48 h, the midgut and fat body were dissected. We used RT-qPCR to monitor the expression of Cactus and REL1 (Toll pathway), IMD, REL2, and Caspar (IMD pathway), STAT and PIAS (JAK-STAT pathway), as well as the expression of antimicrobial peptides (Defensin A, Attacin and Cecropin G). REL1 and REL2 expression in both the midgut and fat body were higher in blood-fed fungus-challenged A. aegypti than in sucrose-fed counterparts. Interestingly, infection of sucrose-fed insects induced Cactus expression in the fat body, a negative regulator of the Toll pathway. The IMD gene was upregulated in the fat body in response to fungal infection after a blood meal. Additionally, we observed the induction of antimicrobial peptides in the blood-fed fungus-challenged insects. This study suggests that blood-fed A. aegypti are less susceptible to fungal infection due to the rapid induction of Toll and IMD immune pathways.

scholarly journals Synergy and remarkable specificity of antimicrobial peptides in vivo using a systematic knockout approach

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Mark Austin Hanson ◽  
Anna Dostálová ◽  
Camilla Ceroni ◽  
Mickael Poidevin ◽  
Shu Kondo ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Fungal Pathogens ◽  
Gene Editing ◽  
Cationic Peptides ◽  
Gram Negative Bacteria ◽  
Biological Processes ◽  
Gram Negative ◽  
Bacteria And Fungi

Antimicrobial peptides (AMPs) are host-encoded antibiotics that combat invading microorganisms. These short, cationic peptides have been implicated in many biological processes, primarily involving innate immunity. In vitro studies have shown AMPs kill bacteria and fungi at physiological concentrations, but little validation has been done in vivo. We utilized CRISPR gene editing to delete most known immune-inducible AMPs of Drosophila, namely: 4 Attacins, 2 Diptericins, Drosocin, Drosomycin, Metchnikowin and Defensin. Using individual and multiple knockouts, including flies lacking these ten AMP genes, we characterize the in vivo function of individual and groups of AMPs against diverse bacterial and fungal pathogens. We found that Drosophila AMPs act primarily against Gram-negative bacteria and fungi, contributing either additively or synergistically. We also describe remarkable specificity wherein certain AMPs contribute the bulk of microbicidal activity against specific pathogens, providing functional demonstrations of highly specific AMP-pathogen interactions in an in vivo setting.

scholarly journals Comparative Effects of Carbapenems on Bacterial Load and Host Immune Response in aKlebsiella pneumoniaeMurine Pneumonia Model

2010 ◽  
Vol 55 (2) ◽  
pp. 836-844 ◽  
Author(s):  
Jamese J. Hilliard ◽  
John L. Melton ◽  
LeRoy Hall ◽  
Darren Abbanat ◽  
Jeffrey Fernandez ◽  
...  
Keyword(s):  
Bacterial Load ◽  
Infection Model ◽  
Antibiotic Resistant ◽  
Gram Negative ◽  
Tissue Sections ◽  
Time Period ◽  
Infection Treatment ◽  
Spectrum Activity ◽  
Broad Spectrum Activity

ABSTRACTDoripenem is a carbapenem with potent broad-spectrum activity against Gram-negative pathogens, including antibiotic-resistantEnterobacteriaceae. As the incidence of extended-spectrum β-lactamase (ESBL)-producing Gram-negative bacilli is increasing, it was of interest to examine thein vivocomparative efficacy of doripenem, imipenem, and meropenem against aKlebsiella pneumoniaeisolate expressing the TEM-26 ESBL enzyme. In a murine lethal lower respiratory infection model, doripenem reduced theKlebsiellalung burden by 2 log10CFU/g lung tissue over the first 48 h of the infection. Treatment of mice with meropenem or imipenem yielded reductions of approximately 1.5 log10CFU/g during this time period. Seven days postinfection,Klebsiellatiters in the lungs of treated mice decreased an additional 2 log10CFU/g relative to those in the lungs of untreated control animals. Lipopolysaccharide (LPS) endotoxin release assays indicated that 6 h postinfection, meropenem- and imipenem-treated animals had 10-fold more endotoxin in lung homogenates and sera than doripenem-treated mice. Following doripenem treatment, the maximum endotoxin release postinfection (6 h) was 53,000 endotoxin units (EU)/ml, which was 2.7- and 6-fold lower than imipenem or meropenem-treated animals, respectively. While the levels of several proinflammatory cytokines increased in both the lungs and sera following intranasalK. pneumoniaeinoculation, doripenem treatment, but not meropenem or imipenem treatment, resulted in significantly increased interleukin 6 levels in lung homogenates relative to those in lung homogenates of untreated controls, which may contribute to enhanced neutrophil killing of bacteria in the lung. Histological examination of tissue sections indicated less overall inflammation and tissue damage in doripenem-treated mice, consistent with improved antibacterial efficacy, reduced LPS endotoxin release, and the observed cytokine induction profile.

scholarly journals Synergy and remarkable specificity of antimicrobial peptides in vivo using a systematic knockout approach

2018 ◽  
Author(s):  
Mark Austin Hanson ◽  
Anna Dostalova ◽  
Camilla Ceroni ◽  
Mickael Poidevin ◽  
Shu Kondo ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Fungal Pathogens ◽  
Gene Editing ◽  
Cationic Peptides ◽  
Gram Negative Bacteria ◽  
Biological Processes ◽  
Gram Negative ◽  
Bacteria And Fungi

Antimicrobial peptides (AMPs) are host-encoded antibiotics that combat invading microorganisms. These short, cationic peptides have been implicated in many biological processes, primarily involving innate immunity. In vitro studies have shown AMPs kill bacteria and fungi at physiological concentrations, but little validation has been done in vivo. We utilised CRISPR gene editing to delete all known immune inducible AMPs of Drosophila, namely: 4 Attacins, 4 Cecropins, 2 Diptericins, Drosocin, Drosomycin, Metchnikowin and Defensin. Using individual and multiple knockouts, including flies lacking all 14 AMP genes, we characterize the in vivo function of individual and groups of AMPs against diverse bacterial and fungal pathogens. We found that Drosophila AMPs act primarily against Gram-negative bacteria and fungi, acting either additively or synergistically. We also describe remarkable specificity wherein certain AMPs contribute the bulk of microbicidal activity against specific pathogens, providing functional demonstrations of highly specific AMP-pathogen interactions in an in vivo setting.

scholarly journals Synergy Between Proline-Rich Antimicrobial Peptides and Small Molecule Antibiotics Against Selected Gram-Negative Pathogens in vitro and in vivo

2018 ◽  
Vol 6 ◽  
Author(s):  
Laszlo Otvos Jr. ◽  
Eszter Ostorhazi ◽  
Dora Szabo ◽  
Steven D. Zumbrun ◽  
Lynda L. Miller ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Small Molecule ◽  
Gram Negative

scholarly journals Antimicrobial Peptides: Virulence and Resistance Modulation in Gram-Negative Bacteria

2020 ◽  
Vol 8 (2) ◽  
pp. 280 ◽  
Author(s):  
Marylise Duperthuy
Keyword(s):  
Antimicrobial Peptides ◽  
Bacterial Resistance ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Low Concentrations ◽  
Resistance Modulation ◽  
Subinhibitory Concentrations ◽  
The Impact

Growing resistance to antibiotics is one of the biggest threats to human health. One of the possibilities to overcome this resistance is to use and develop alternative molecules such as antimicrobial peptides (AMPs). However, an increasing number of studies have shown that bacterial resistance to AMPs does exist. Since AMPs are immunity molecules, it is important to ensure that their potential therapeutic use is not harmful in the long term. Recently, several studies have focused on the adaptation of Gram-negative bacteria to subinhibitory concentrations of AMPs. Such concentrations are commonly found in vivo and in the environment. It is therefore necessary to understand how bacteria detect and respond to low concentrations of AMPs. This review focuses on recent findings regarding the impact of subinhibitory concentrations of AMPs on the modulation of virulence and resistance in Gram-negative bacteria.

scholarly journals Augmentation of Innate Host Defense by Expression of a Cathelicidin Antimicrobial Peptide

1999 ◽  
Vol 67 (11) ◽  
pp. 6084-6089 ◽  
Author(s):  
Robert Bals ◽  
Daniel J. Weiner ◽  
A. David Moscioni ◽  
Rupalie L. Meegalla ◽  
James M. Wilson
Keyword(s):  
Antimicrobial Peptides ◽  
Antimicrobial Peptide ◽  
Intravenous Injection ◽  
Host Defense ◽  
Recombinant Adenovirus ◽  
Bacterial Load ◽  
Survival Rates ◽  
Innate Immune

ABSTRACT Antimicrobial peptides, such as defensins or cathelicidins, are effector substances of the innate immune system and are thought to have antimicrobial properties that contribute to host defense. The evidence that vertebrate antimicrobial peptides contribute to innate immunity in vivo is based on their expression pattern and in vitro activity against microorganisms. The goal of this study was to investigate whether the overexpression of an antimicrobial peptide results in augmented protection against bacterial infection. C57BL/6 mice were given an adenovirus vector containing the cDNA for LL-37/hCAP-18, a human cathelicidin antimicrobial peptide. Mice treated with intratracheal LL-37/hCAP-18 vector had a lower bacterial load and a smaller inflammatory response than did untreated mice following pulmonary challenge with Pseudomonas aeruginosa PAO1. Systemic expression of LL-37/hCAP-18 after intravenous injection of recombinant adenovirus resulted in improved survival rates following intravenous injection of lipopolysaccharide with galactosamine or Escherichia coli CP9. In conclusion, the data demonstrate that expression of an antimicrobial peptide by gene transfer results in augmentation of the innate immune response, providing support for the hypothesis that vertebrate antimicrobial peptides protect against microorganisms in vivo.

scholarly journals Synthetic molecular evolution of host cell-compatible, antimicrobial peptides effective against drug-resistant, biofilm-forming bacteria

2020 ◽  
Vol 117 (15) ◽  
pp. 8437-8448 ◽  
Author(s):  
Charles G. Starr ◽  
Jenisha Ghimire ◽  
Shantanu Guha ◽  
Joseph P. Hoffmann ◽  
Yihui Wang ◽  
...  
Keyword(s):  
Molecular Evolution ◽  
Antimicrobial Peptides ◽  
Host Cell ◽  
Host Cells ◽  
Resistant Bacteria ◽  
Antibiofilm Activity ◽  
Drug Resistant ◽  
Gram Positive ◽  
Gram Negative

Novel classes of antibiotics and new strategies to prevent and treat infections are urgently needed because the rapid rise in drug-resistant bacterial infections in recent decades has been accompanied by a parallel decline in development of new antibiotics. Membrane permeabilizing antimicrobial peptides (AMPs) have long been considered a potentially promising, novel class of antibiotic, especially for wound protection and treatment to prevent the development of serious infections. Yet, despite thousands of known examples, AMPs have only infrequently proceeded as far as clinical trials, especially the chemically simple, linear examples. In part, this is due to impediments that often limit their applications in vivo. These can include low solubility, residual toxicity, susceptibility to proteolysis, and loss of activity due to host cell, tissue, and protein binding. Here we show how synthetic molecular evolution can be used to evolve potentially advantageous antimicrobial peptides that lack these impediments from parent peptides that have at least some of them. As an example of how the antibiotic discovery pipeline can be populated with more promising candidates, we evolved and optimized one family of linear AMPs into a new generation with high solubility, low cytotoxicity, potent broad-spectrum sterilizing activity against a panel of gram-positive and gram-negative ESKAPE pathogens, and antibiofilm activity against gram-positive and gram-negative biofilms. The evolved peptides have these activities in vitro even in the presence of concentrated host cells and also in vivo in the complex, cell- and protein-rich environment of a purulent animal wound model infected with drug-resistant bacteria.

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