scholarly journals Efficient Killing of Multidrug-Resistant Intracellular Bacteria by AIEgens in Vivo

2020 ◽  
Author(s):  
Ying Li ◽  
Fei Liu ◽  
Jiangjiang Zhang ◽  
Xiaoye Liu ◽  
Peihong Xiao ◽  
...  
Keyword(s):  
Membrane Damage ◽  
Multidrug Resistant ◽  
Host Cells ◽  
Comparable Efficacy ◽  
Intracellular Bacteria ◽  
New Agents ◽  
Immune Clearance ◽  
Infected Cells ◽  
Dose Levels

<p><a>Bacteria infected cells acting as “Trojan horses” not only protect bacteria from antibiotic therapies and immune clearance, but also increase the dissemination of pathogens from the initial sites of infection. Antibiotics are hard and insufficient to treat such hidden intracellular bacteria, especially the multidrug</a>-resistant (MDR) bacteria. Herein, aggregation-induced emission luminogens (AIEgens) such as TBPs showed potent broad-spectrum bactericidal activity against both <a></a><a>extracellular and intracellular</a> Gram-positive pathogens at low-dose levels. TBPs triggered reactive oxygen species (ROS)-mediated membrane damage to kill bacteria, regardless of light irradiation. Additionally, such AIEgens activated mitochondria dependent autophagy to eliminate intracellular bacteria in host cells. Compared to the routinely used vancomycin in clinics, TBPs showed comparable efficacy against methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) <i>in vivo</i>. Our studies demonstrate that AIEgens are promising new agents for the treatment of MDR bacteria associated infections.</p>

scholarly journals Efficient Killing of Multidrug-Resistant Intracellular Bacteria by AIEgens in Vivo

2020 ◽  
Author(s):  
Ying Li ◽  
Fei Liu ◽  
Jiangjiang Zhang ◽  
Xiaoye Liu ◽  
Peihong Xiao ◽  
...  
Keyword(s):  
Membrane Damage ◽  
Multidrug Resistant ◽  
Host Cells ◽  
Comparable Efficacy ◽  
Intracellular Bacteria ◽  
New Agents ◽  
Immune Clearance ◽  
Infected Cells ◽  
Dose Levels

<p><a>Bacteria infected cells acting as “Trojan horses” not only protect bacteria from antibiotic therapies and immune clearance, but also increase the dissemination of pathogens from the initial sites of infection. Antibiotics are hard and insufficient to treat such hidden intracellular bacteria, especially the multidrug</a>-resistant (MDR) bacteria. Herein, aggregation-induced emission luminogens (AIEgens) such as TBPs showed potent broad-spectrum bactericidal activity against both <a></a><a>extracellular and intracellular</a> Gram-positive pathogens at low-dose levels. TBPs triggered reactive oxygen species (ROS)-mediated membrane damage to kill bacteria, regardless of light irradiation. Additionally, such AIEgens activated mitochondria dependent autophagy to eliminate intracellular bacteria in host cells. Compared to the routinely used vancomycin in clinics, TBPs showed comparable efficacy against methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) <i>in vivo</i>. Our studies demonstrate that AIEgens are promising new agents for the treatment of MDR bacteria associated infections.</p>

scholarly journals Compartmentalization of the Broad-Range Phospholipase C Activity to the Spreading Vacuole Is Critical for Listeria monocytogenes Virulence

2006 ◽  
Vol 75 (1) ◽  
pp. 44-51 ◽  
Author(s):  
P. S. Marie Yeung ◽  
Yoojin Na ◽  
Amanda J. Kreuder ◽  
Hélène Marquis
Keyword(s):  
Listeria Monocytogenes ◽  
Phospholipase C ◽  
Membrane Damage ◽  
Bacterial Pathogen ◽  
Host Cells ◽  
Virulence Attenuation ◽  
Infected Cells ◽  
Host Cell Membranes ◽  
Cell Spread

ABSTRACT Listeria monocytogenes is a bacterial pathogen that multiplies in the cytosol of host cells and spreads directly from cell to cell by using an actin-based mechanism of motility. The broad-range phospholipase C (PC-PLC) of L. monocytogenes contributes to bacterial escape from vacuoles formed upon cell-to-cell spread. PC-PLC is made as an inactive proenzyme whose activation requires cleavage of an N-terminal propeptide. During infection, PC-PLC is activated specifically in acidified vacuoles. To assess the importance of compartmentalizing PC-PLC activity during infection, we created a mutant that makes constitutively active PC-PLC (the plcBΔpro mutant). Results from intracellular growth and cell-to-cell spread assays showed that the plcBΔpro mutant was sensitive to gentamicin, suggesting that unregulated PC-PLC activity causes damage to host cell membranes. This was confirmed by the observation of a twofold increase in staining of live infected cells by a non-membrane-permeant DNA fluorescent dye. However, membrane damage was not sufficient to cause cell lysis and was dependent on bacterial cell-to-cell spread, suggesting that damage was localized to bacterium-containing filopodia. Using an in vivo competitive infection assay, we observed that the plcBΔpro mutant was outcompeted up to 200-fold by the wild-type strain in BALB/c mice. Virulence attenuation was greater when mice were infected orally than when they were infected intravenously, presumably because the plcBΔpro mutant was initially outcompeted in the intestines, reducing the number of mutant bacteria reaching the liver and spleen. Together, these results emphasize the importance for L. monocytogenes virulence of compartmentalizing the activity of PC-PLC during infection.

scholarly journals An infection-induced RhoB-Beclin 1-Hsp90 complex enhances clearance of uropathogenic Escherichia coli

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chunhui Miao ◽  
Mingyu Yu ◽  
Geng Pei ◽  
Zhenyi Ma ◽  
Lisong Zhang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Treatment Strategies ◽  
Uropathogenic Escherichia Coli ◽  
Beclin 1 ◽  
Host Cells ◽  
Infection Model ◽  
Intracellular Bacteria ◽  
Bladder Epithelium ◽  
Binding Residue

AbstractHost cells use several anti-bacterial pathways to defend against pathogens. Here, using a uropathogenic Escherichia coli (UPEC) infection model, we demonstrate that bacterial infection upregulates RhoB, which subsequently promotes intracellular bacteria clearance by inducing LC3 lipidation and autophagosome formation. RhoB binds with Beclin 1 through its residues at 118 to 140 and the Beclin 1 CCD domain, with RhoB Arg133 being the key binding residue. Binding of RhoB to Beclin 1 enhances the Hsp90-Beclin 1 interaction, preventing Beclin 1 degradation. RhoB also directly interacts with Hsp90, maintaining RhoB levels. UPEC infections increase RhoB, Beclin 1 and LC3 levels in bladder epithelium in vivo, whereas Beclin 1 and LC3 levels as well as UPEC clearance are substantially reduced in RhoB+/− and RhoB−/− mice upon infection. We conclude that when stimulated by UPEC infections, host cells promote UPEC clearance through the RhoB-Beclin 1-HSP90 complex, indicating RhoB may be a useful target when developing UPEC treatment strategies.

scholarly journals In vivo analysis of influenza A mRNA secondary structures identifies critical regulatory motifs

2019 ◽  
Vol 47 (13) ◽  
pp. 7003-7017 ◽  
Author(s):  
Lisa Marie Simon ◽  
Edoardo Morandi ◽  
Anna Luganini ◽  
Giorgio Gribaudo ◽  
Luis Martinez-Sobrido ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Influenza A ◽  
Host Cells ◽  
Messenger Rnas ◽  
Infected Cells ◽  
In Vivo Analysis ◽  
First Time ◽  
Negative Sense

AbstractThe influenza A virus (IAV) is a continuous health threat to humans as well as animals due to its recurring epidemics and pandemics. The IAV genome is segmented and the eight negative-sense viral RNAs (vRNAs) are transcribed into positive sense complementary RNAs (cRNAs) and viral messenger RNAs (mRNAs) inside infected host cells. A role for the secondary structure of IAV mRNAs has been hypothesized and debated for many years, but knowledge on the structure mRNAs adopt in vivo is currently missing. Here we solve, for the first time, the in vivo secondary structure of IAV mRNAs in living infected cells. We demonstrate that, compared to the in vitro refolded structure, in vivo IAV mRNAs are less structured but exhibit specific locally stable elements. Moreover, we show that the targeted disruption of these high-confidence structured domains results in an extraordinary attenuation of IAV replicative capacity. Collectively, our data provide the first comprehensive map of the in vivo structural landscape of IAV mRNAs, hence providing the means for the development of new RNA-targeted antivirals.

scholarly journals Deubiquitinating Function of Adenovirus Proteinase

2002 ◽  
Vol 76 (12) ◽  
pp. 6323-6331 ◽  
Author(s):  
Maxim Y. Balakirev ◽  
Michel Jaquinod ◽  
Arthur L. Haas ◽  
Jadwiga Chroboczek
Keyword(s):  
Structural Model ◽  
Proteolytic Processing ◽  
Host Cells ◽  
Cellular Proteins ◽  
Viral Gene ◽  
Cellular Processes ◽  
Infected Cells ◽  
Substrate Binding Sites

ABSTRACT The invasion strategy of many viruses involves the synthesis of viral gene products that mimic the functions of the cellular proteins and thus interfere with the key cellular processes. Here we show that adenovirus infection is accompanied by an increased ubiquitin-cleaving (deubiquitinating) activity in the host cells. Affinity chromatography on ubiquitin aldehyde (Ubal), which was designed to identify the deubiquitinating proteases, revealed the presence of adenovirus L3 23K proteinase (Avp) in the eluate from adenovirus-infected cells. This proteinase is known to be necessary for the processing of viral precursor proteins during virion maturation. We show here that in vivo Avp deubiquitinates a number of cellular proteins. Analysis of the substrate specificity of Avp in vitro demonstrated that the protein deubiquitination by this enzyme could be as efficient as proteolytic processing of viral proteins. The structural model of the Ubal-Avp interaction revealed some similarity between S1-S4 substrate binding sites of Avp and ubiquitin hydrolases. These results may reflect the acquisition of an advantageous property by adenovirus and may indicate the importance of ubiquitin pathways in viral infection.

scholarly journals Strategies to Investigate Membrane Damage, Nucleoid Condensation, and RNase Activity of Bacterial Toxin–Antitoxin Systems

2021 ◽  
Vol 4 (4) ◽  
pp. 71
Author(s):  
Stefano Maggi ◽  
Alberto Ferrari ◽  
Korotoum Yabre ◽  
Aleksandra Anna Bonini ◽  
Claudio Rivetti ◽  
...  
Keyword(s):  
Cell Transformation ◽  
Expression System ◽  
Membrane Damage ◽  
Membrane Integrity ◽  
Host Cells ◽  
Rnase Activity ◽  
Bacterial Toxin ◽  
Type I

A large number of bacterial toxin–antitoxin (TA) systems have been identified so far and different experimental approaches have been explored to investigate their activity and regulation both in vivo and in vitro. Nonetheless, a common feature of these methods is represented by the difficulty in cell transformation, culturing, and stability of the transformants, due to the expression of highly toxic proteins. Recently, in dealing with the type I Lpt/RNAII and the type II YafQ/DinJ TA systems, we encountered several of these problems that urged us to optimize methodological strategies to study the phenotype of recombinant Escherichia coli host cells. In particular, we have found conditions to tightly repress toxin expression by combining the pET expression system with the E. coli C41(DE3) pLysS strain. To monitor the RNase activity of the YafQ toxin, we developed a fluorescence approach based on Thioflavin-T which fluoresces brightly when complexed with bacterial RNA. Fluorescence microscopy was also applied to reveal loss of membrane integrity associated with the activity of the type I toxin Lpt, by using DAPI and ethidium bromide to selectively stain cells with impaired membrane permeability. We further found that atomic force microscopy can readily be employed to characterize toxin-induced membrane damages.

scholarly journals Development of a Conserved Chimeric Vaccine for Induction of Strong Immune Response against Staphylococcus aureus Using Immunoinformatics Approaches

Vaccines ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1038
Author(s):  
Rahul Chatterjee ◽  
Panchanan Sahoo ◽  
Soumya Ranjan Mahapatra ◽  
Jyotirmayee Dey ◽  
Mrinmoy Ghosh ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Immune Response ◽  
Multidrug Resistant ◽  
Host Cells ◽  
Dynamics Simulation ◽  
Population Coverage ◽  
Strong Immune Response ◽  
Chimeric Vaccine

Staphylococcus aureus is one of the most notorious Gram-positive bacteria with a very high mortality rate. The WHO has listed S. aureus as one of the ESKAPE pathogens requiring urgent research and development efforts to fight against it. Yet there is a major layback in the advancement of effective vaccines against this multidrug-resistant pathogen. SdrD and SdrE proteins are attractive immunogen candidates as they are conserved among all the strains and contribute specifically to bacterial adherence to the host cells. Furthermore, these proteins are predicted to be highly antigenic and essential for pathogen survival. Therefore, in this study, using the immunoinformatics approach, a novel vaccine candidate was constructed using highly immunogenic conserved T-cell and B-cell epitopes along with specific linkers, adjuvants, and consequently modeled for docking with human Toll-like receptor 2. Additionally, physicochemical properties, secondary structure, disulphide engineering, and population coverage analysis were also analyzed for the vaccine. The constructed vaccine showed good results of worldwide population coverage and a promising immune response. For evaluation of the stability of the vaccine-TLR-2 docked complex, a molecular dynamics simulation was performed. The constructed vaccine was subjected to in silico immune simulations by C-ImmSim and Immune simulation significantly provided high levels of immunoglobulins, T-helper cells, T-cytotoxic cells, and INF-γ. Lastly, upon cloning, the vaccine protein was reverse transcribed into a DNA sequence and cloned into a pET28a (+) vector to ensure translational potency and microbial expression. The overall results of the study showed that the designed novel chimeric vaccine can simultaneously elicit humoral and cell-mediated immune responses and is a reliable construct for subsequent in vivo and in vitro studies against the pathogen.

scholarly journals Glycosylation-dependent galectin–receptor interactions promoteChlamydia trachomatisinfection

2018 ◽  
Vol 115 (26) ◽  
pp. E6000-E6009 ◽  
Author(s):  
Agustin L. Lujan ◽  
Diego O. Croci ◽  
Julián A. Gambarte Tudela ◽  
Antonella D. Losinno ◽  
Alejandro J. Cagnoni ◽  
...  
Keyword(s):  
Host Cell ◽  
Host Cells ◽  
Bacterial Invasion ◽  
Tubal Infertility ◽  
Sexually Transmitted ◽  
Multiple Strategies ◽  
Host Cell Interactions ◽  
Infected Cells ◽  
Obligate Intracellular Pathogen

Chlamydia trachomatis(Ct) constitutes the most prevalent sexually transmitted bacterium worldwide. Chlamydial infections can lead to severe clinical sequelae including pelvic inflammatory disease, ectopic pregnancy, and tubal infertility. As an obligate intracellular pathogen,Cthas evolved multiple strategies to promote adhesion and invasion of host cells, including those involving both bacterial and host glycans. Here, we show that galectin-1 (Gal1), an endogenous lectin widely expressed in female and male genital tracts, promotesCtinfection. Through glycosylation-dependent mechanisms involving recognition of bacterial glycoproteins andN-glycosylated host cell receptors, Gal1 enhancedCtattachment to cervical epithelial cells. Exposure to Gal1, mainly in its dimeric form, facilitated bacterial entry and increased the number of infected cells by favoringCt–CtandCt–host cell interactions. These effects were substantiated in vivo in mice lacking Gal1 or complex β1–6-branchedN-glycans. Thus, disrupting Gal1–N-glycan interactions may limit the severity of chlamydial infection by inhibiting bacterial invasion of host cells.

scholarly journals Trypanosoma cruziPosttranscriptionally Up-Regulates and Exploits Cellular FLIP for Inhibition of Death-inducing Signal

2005 ◽  
Vol 16 (8) ◽  
pp. 3521-3528 ◽  
Author(s):  
Muneaki Hashimoto ◽  
Junko Nakajima-Shimada ◽  
Takashi Aoki
Keyword(s):  
Death Receptor ◽  
Protozoan Parasite ◽  
Host Cells ◽  
Mouse Heart ◽  
Inhibitory Protein ◽  
Protozoan Infection ◽  
Heart Muscle Cells ◽  
Infected Cells ◽  
Interfering Rna

Intracellular persistence of the protozoan parasite, Trypanosoma cruzi, is an aggravating cause of Chagas' disease, involving that the protozoan infection specifically inhibits death receptor-mediated apoptosis of host cells. Here we demonstrate that the parasite dramatically up-regulates cellular FLICE inhibitory protein (c-FLIP), the only known mammalian inhibitor specific for death receptor signaling, in infected cells by an unusual, posttranscriptional stabilization of the short-lived protein. We also show that c-FLIP is accumulated in T. cruzi–infected mouse heart muscle cells in vivo. Stimulation of death receptor Fas in infected cells induces recruitment of c-FLIP to block the procaspase-8 activation at the most upstream caspase cascade. c-FLIP knock-down with a small interfering RNA significantly restores Fas-mediated apoptosis in infected cells. Taken together, our findings indicate that T. cruzi posttranscriptionally up-regulates and exploits host c-FLIP for the inhibition of death-inducing signal, a mechanism that may allow parasites to persist in host cells.

scholarly journals The Role of Mcl-1 inS. aureus-Induced Cytoprotection of Infected Macrophages

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Joanna Koziel ◽  
Katarzyna Kmiecik ◽  
Daniela Chmiest ◽  
Katarzyna Maresz ◽  
Danuta Mizgalska ◽  
...  
Keyword(s):  
De Novo ◽  
Myeloid Cell ◽  
Underlying Mechanism ◽  
Host Cells ◽  
Intracellular Pathogen ◽  
Dependent Inhibition ◽  
Infected Cells ◽  
The Stability

As a facultative intracellular pathogen,Staphylococcus aureusinvades macrophages and then promotes the cytoprotection of infected cells thus stabilizing safe niche for silent persistence. This process occurs through the upregulation of crucial antiapoptotic genes, in particular,myeloid cell leukemia-1 (MCL-1). Here, we investigated the underlying mechanism and signal transduction pathways leading to increasedMCL-1expression in infected macrophages. LiveS. aureusnot only stimulatedde novosynthesis of Mcl-1, but also prolonged the stability of this antiapoptotic protein. Consistent with this, we proved a crucial role of Mcl-1 inS. aureus-induced cytoprotection, since silencing ofMCL1by siRNA profoundly reversed the cytoprotection of infected cells leading to apoptosis. IncreasedMCL1expression in infected cells was associated with enhanced NFκB activation and subsequent IL-6 secretion, since the inhibition of both NFκB and IL-6 signalling pathways abrogated Mcl-1 induction and cytoprotection. Finally, we confirmed our observationin vivoin murine model of septic arthritis showing the association between the severity of arthritis and Mcl-1 expression. Therefore, we propose thatS. aureusis hijacking the Mcl-1-dependent inhibition of apoptosis to prevent the elimination of infected host cells, thus allowing the intracellular persistence of the pathogen, its dissemination by infected macrophages, and the progression of staphylococci diseases.

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