scholarly journals Identification of a Human Anti-Alpha-Toxin Monoclonal Antibody Against Staphylococcus aureus Infection

2021 ◽  
Vol 12 ◽  
Author(s):  
Fangjie Liu ◽  
Zhangchun Guan ◽  
Yu Liu ◽  
Jingjing Li ◽  
Chenghua Liu ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Monoclonal Antibody ◽  
A549 Cells ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Phage Display Technology ◽  
Alpha Hemolysin ◽  
Protective Strategy ◽  
Display Technology ◽  
Hla Binding

Staphylococcus aureus is a major pathogenic bacterium that causes a variety of clinical infections. The emergence of multi-drug resistant mechanisms requires novel strategies to mitigate S. aureus infection. Alpha-hemolysin (Hla) is a key virulence factor that is believed to play a significant role in the pathogenesis of S. aureus infections. In this study, we screened a naïve human Fab library for identification of monoclonal antibodies targeting Hla by phage display technology. We found that the monoclonal antibody YG1 blocked the Hla-mediated lysis of rabbit red blood cells and inhibited Hla binding to A549 cells in a concentration-dependent manner. YG1 also provided protection against acute peritoneal infection, bacteremia, and pneumonia in murine models. We further characterized its epitope using different Hla variants and found that the amino acids N209 and F210 of Hla were functionally and structurally important for YG1 binding. Overall, these results indicated that targeting Hla with YG1 could serve as a promising protective strategy against S. aureus infection.

scholarly journals Subinhibitory Concentrations of Prim-O-Glucosylcimifugin Decrease the Expression of Alpha-Hemolysin inStaphylococcus aureus(USA300)

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Ouyang Ping ◽  
Yang Ruixue ◽  
Deng Jiaqiang ◽  
Wang Kaiyu ◽  
Fang Jing ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
A549 Cells ◽  
Opportunistic Pathogen ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Rt Pcr ◽  
Chinese Medicines ◽  
Alpha Hemolysin ◽  
Subinhibitory Concentrations ◽  
Dose Dependent

Staphylococcus aureus (S. aureus), an important opportunistic pathogen in human and animal, causes a series of diseases in the impairing of immunity of host and even then death. Alpha-hemolysin (Hla), a primary virulence factor, plays a major role in the pathogenic progress ofS. aureus, especially in pneumonia. Prim-O-glucosylcimifugin (POG), a nature chromone compound, is an active ingredient in many Chinese Medicines. In this study, POG investigated the inhibitory effect of the secretion of Hla inS. aureusstrain USA300 at the subinhibitory concentrations. The hemolysis assays and western blotting assays showed that POG can decrease the production of Hla in the USA300 growth cell cultures in a dose-dependent manner. The results of RT-PCR revealed that reduction of Hla was related to inhibit the transcription ofhlaandRNAIII. In the cells experiment, POG was proved to protect A549 cells from Hla-medicated injury. In conclusion, POG was shown the capacity of decreased the production ofS. aureusHla. POG can be developed as a candidate agent to treatS. aureusinfections against Hla.

scholarly journals Cytotoxic Effects of Flubendazole in Human Lung Cancer Cell Line A549

2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Elham Hoveizi ◽  
Fatemeh Fakharzadeh Jahromi
Keyword(s):  
Lung Cancer ◽  
Cell Viability ◽  
Human Lung ◽  
A549 Cells ◽  
Beclin 1 ◽  
Human Lung Cancer ◽  
Pcr Analysis ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Acridine Orange Staining

Background: The development of effective anticancer drugs is a significant health issue. Previous studies showed that members of the benzimidazole family have anticancer effects on several cancers Objectives: The present study investigated the cytotoxic effect of flubendazole on A549 human lung cancer cells. Methods: The A549 cells were treated with flubendazole at 1, 2, 5, and 10 µM concentrations for three days. Cell viability was measured by the MTT assay and Acridine orange staining. Also, the expressions of P62 and Beclin -1 were analyzed by qRT-PCR analysis. Results: Cell viability of A549 cells, in a concentration-dependent manner, showed significant differences between the treatment and control groups, and the IC50 value was determined to be 2 µM. Also, flubendazole reduced the expression of P62 and increased the expression of Beclin 1 in treated cells. Conclusions: Flubendazole induces cell death in A549 cells in a dose and time-dependent manner and can offer new factors in lung cancer therapeutic strategies.

Synthesis and Biological Evaluation of Novel 4-Phenylaminobenzofuro[2,3-d]pyrimidine Derivatives

2020 ◽  
Vol 42 (4) ◽  
pp. 564-564
Author(s):  
Ju liu Ju liu ◽  
Jun Li Jun Li ◽  
Jian tao Shi Jian tao Shi ◽  
Jie Li Jie Li ◽  
Xue chen Hao Xue chen Hao ◽  
...  
Keyword(s):  
Cell Lines ◽  
A549 Cells ◽  
Positive Control ◽  
Biological Evaluation ◽  
Dependent Manner ◽  
Pyrimidine Derivatives ◽  
Concentration Dependent Manner ◽  
Ic50 Value ◽  
Synthesis And Biological Evaluation

A series of novel 4-phenylaminobenzofuro[2,3-d]pyrimidine derivatives had been prepared and assessed for their in vitro antiproliferative activities against three lung cancer cell lines (A549, H460 and H1975). The bioassay results showed most of the designed compounds exhibited potential antiproliferation activities. Among them, compound 8f exhibited remarkable inhibitory activity against A549 and H460 cell lines with IC50 value of 2.54 μM and 2.68 μM, respectively, which was comparable to that of the positive control sorafenib (IC50 = 2.69 μM for A549 and 3.71 μM for H460). AO/EB staining suggests that compound 8f could induce apoptosis in A549 cells. Furthermore, cell cycle analyses show that compound 8f increased G0/G1 A549 cells arrest in a concentration-dependent manner. The preliminary structure-activity relationships (SARs) studies indicated that mono-electron-withdrawing groups (mono-EWGs) on the phenyl ring are positive on the antitumor activity.

scholarly journals Design, Synthesis and Biological Evaluation of a New Series of 1-Aryl-3-{4-[(pyridin-2-ylmethyl)thio]phenyl}urea Derivatives as Antiproliferative Agents

Molecules ◽  
2019 ◽  
Vol 24 (11) ◽  
pp. 2108 ◽  
Author(s):  
Chuanming Zhang ◽  
Xiaoyu Tan ◽  
Jian Feng ◽  
Ning Ding ◽  
Yongpeng Li ◽  
...  
Keyword(s):  
Cell Lines ◽  
Cancer Cell ◽  
A549 Cells ◽  
Cancer Cell Lines ◽  
Biological Evaluation ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Urea Derivatives ◽  
Antiproliferative Agents

To discover new antiproliferative agents with high efficacy and selectivity, a new series of 1-aryl-3-{4-[(pyridin-2-ylmethyl)thio]phenyl}urea derivatives (7a–7t) were designed, synthesized and evaluated for their antiproliferative activity against A549, HCT-116 and PC-3 cancer cell lines in vitro. Most of the target compounds demonstrated significant antiproliferative effects on all the selective cancer cell lines. Among them, the target compound, 1-[4-chloro-3-(trifluoromethyl)phenyl]-3-{4-{{[3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl]methyl}thio}phenyl}urea (7i) was identified to be the most active one against three cell lines, which was more potent than the positive control with an IC50 value of 1.53 ± 0.46, 1.11 ± 0.34 and 1.98 ± 1.27 μM, respectively. Further cellular mechanism studies confirmed that compound 7i could induce the apoptosis of A549 cells in a concentration-dependent manner and elucidated compound 7i arrests cell cycle at G1 phase by flow cytometry analysis. Herein, the studies suggested that the 1-aryl-3-{4-[(pyridin-2-ylmethyl)thio]phenyl}urea skeleton might be regarded as new chemotypes for designing effective antiproliferative agents.

An Alanine-Rich Peptide Attenuates Quorum Sensing-Regulated Virulence and Biofilm Formation in Staphylococcus aureus

2019 ◽  
Vol 102 (4) ◽  
pp. 1228-1234 ◽  
Author(s):  
Raid Al Akeel ◽  
Ayesha Mateen ◽  
Rabbani Syed
Keyword(s):  
Gene Expression ◽  
Staphylococcus Aureus ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Bacterial Attachment ◽  
The Body ◽  
Dependent Manner ◽  
Virulence Determinants ◽  
Microarray Gene Expression ◽  
Concentration Dependent Manner

Abstract Background: Alanine-rich proteins/peptides (ARP), with bioactivity of up to 20 amino acid residues, can be observed by the body easily during gastrointestinal digestion. Objective: Populus trichocarpa extract’s capability to attenuate quorum sensing-regulated virulence and biofilm formation in Staphylococcus aureus is described. Methods: PT13, an ARP obtained from P. trichocarpa, was tested for its activity against S. aureus using the broth microdilution test; a crystal-violet biofilm assay was performed under a scanning electron microscope. The production of various virulence factors was estimated with PT13 treatment. Microarray gene expression profiling of PT13-treated S. aureus was conducted and compared with an untreated control. Exopolysaccharides (EPS) was estimated to observe the PT13 inhibition activity. Results: PT13 was antimicrobial toward S. aureus at different concentrations and showed a similar growth rate in the presence and absence of PT13 at concentrations ≤8 μg/mL. Biofilm production was interrupted even at low concentrations, and biofilm-related genes were down-regulated when exposed to PT13. The genes encoding cell adhesion and bacterial attachment protein were the major genes suppressed by PT13. In addition, hemolysins, clumping activity, and EPS production of S. aureus decreased after treatment in a concentration-dependent manner. Conclusions: A long-chain PT13 with effective actions that, even at low concentration levels, not only regulated the gene expression in the producer organism but also blocked the virulence gene expression in this Gram-positive human pathogen is described. Highlights: We identified a PT13 as a potential antivirulence agent that regulated production of bacterial virulence determinants (e.g., toxins, enzymes and biofilm), downwards and it may be a promising anti-virulence agent to be further developed as an anti-infective agent.

scholarly journals PYED-1 Inhibits Biofilm Formation and Disrupts the Preformed Biofilm of Staphylococcus aureus

Antibiotics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 240 ◽  
Author(s):  
Adriana Vollaro ◽  
Anna Esposito ◽  
Eliana Pia Esposito ◽  
Raffaele Zarrilli ◽  
Annalisa Guaragna ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Surface Proteins ◽  
Transcriptional Analysis ◽  
Capsular Polysaccharides ◽  
Dependent Manner ◽  
Chronic Infections ◽  
Concentration Dependent Manner ◽  
Expression Of Genes

Pregnadiene-11-hydroxy-16α,17α-epoxy-3,20-dione-1 (PYED-1), a heterocyclic corticosteroid derivative of deflazacort, exhibits broad-spectrum antibacterial activity against Gram-negative and Gram-positive bacteria. Here, we investigated the effect of PYED-1 on the biofilms of Staphylococcus aureus, an etiological agent of biofilm-based chronic infections such as osteomyelitis, indwelling medical device infections, periodontitis, chronic wound infections, and endocarditis. PYED-1 caused a strong reduction in biofilm formation in a concentration dependent manner. Furthermore, it was also able to completely remove the preformed biofilm. Transcriptional analysis performed on the established biofilm revealed that PYED-1 downregulates the expression of genes related to quorum sensing (agrA, RNAIII, hld, psm, and sarA), surface proteins (clfB and fnbB), secreted toxins (hla, hlb, and lukD), and capsular polysaccharides (capC). The expression of genes that encode two main global regulators, sigB and saeR, was also significantly inhibited after treatment with PYED-1. In conclusion, PYED-1 not only effectively inhibited biofilm formation, but also eradicated preformed biofilms of S. aureus, modulating the expression of genes related to quorum sensing, surface and secreted proteins, and capsular polysaccharides. These results indicated that PYED-1 may have great potential as an effective antibiofilm agent to prevent S. aureus biofilm-associated infections.

scholarly journals Glucosamine Hydrochloride Specifically Inhibits COX-2 by Preventing COX-2 N-Glycosylation and by Increasing COX-2 Protein Turnover in a Proteasome-dependent Manner

2007 ◽  
Vol 282 (38) ◽  
pp. 27622-27632 ◽  
Author(s):  
Byeong-Churl Jang ◽  
Su-Haeng Sung ◽  
Jong-Gu Park ◽  
Jong-Wook Park ◽  
Jae Hoon Bae ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Protein Turnover ◽  
A549 Cells ◽  
Lung Epithelial Cells ◽  
Prostaglandin E ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Glucosamine Hydrochloride ◽  
Cox 2 ◽  
Factor Α

COX-2 and its products, including prostaglandin E2, are involved in many inflammatory processes. Glucosamine (GS) is an amino monosaccharide and has been widely used for alternative regimen of (osteo) arthritis. However, the mechanism of action of GS on COX-2 expression remains unclear. Here we describe a new action mechanism of glucosamine hydrochloride (GS-HCl) to tackle endogenous and agonistdriven COX-2 at protein level. GS-HCl (but not GS sulfate, N-acetyl GS, or galactosamine HCl) resulted in a shift in the molecular mass of COX-2 from 72–74 to 66–70 kDa and concomitant inhibition of prostaglandin E2 production in a concentration-dependent manner in interleukin (IL)-1β-treated A549 human lung epithelial cells. Remarkably, GS-HCl-mediated decrease in COX-2 molecular mass was associated with inhibition of COX-2 N-glycosylation during translation, as assessed by the effect of tunicamycin, the protein N-glycosylation inhibitor, or of cycloheximide, the translation inhibitor, on COX-2 modification. Specifically, the effect of low concentration of GS-HCl (1 mm) or of tunicamycin (0.1 μg/ml) to produce the aglycosylated COX-2 was rescued by the proteasomal inhibitor MG132 but not by the lysosomal or caspase inhibitors. However, the proteasomal inhibitors did not show an effect at 5 mm GS-HCl, which produced the aglycosylated or completely deglycosylated form of COX-2. Notably, GS-HCl (5 mm) also facilitated degradation of the higher molecular species of COX-2 in IL-1β-treated A549 cells that was retarded by MG132. GS-HCl (5 mm) was also able to decrease the molecular mass of endogenous and IL-1β- or tumor necrosis factor-α-driven COX-2 in different human cell lines, including Hep2 (bronchial) and H292 (laryngeal). However, GS-HCl did not affect COX-1 protein expression. These results demonstrate for the first time that GS-HCl inhibits COX-2 activity by preventing COX-2 co-translational N-glycosylation and by facilitating COX-2 protein turnover during translation in a proteasome-dependent manner.

scholarly journals Differential effects of antibiotics on neutrophils exposed to lipoteichoic acid derived from Staphylococcus aureus

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Marquerita Algorri ◽  
Annie Wong-Beringer
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Agents ◽  
Lipoteichoic Acid ◽  
Neutrophil Function ◽  
Exposure Level ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Persistent Bacteremia ◽  
Neutrophil Survival

Abstract Background Persistent bacteremia occurs in at least 30% of patients with Staphylococcus aureus bloodstream infection (SAB) and may be attributable to a dysregulated host immune response. Neutrophils interact with a variety of S. aureus microbial factors, including lipoteichoic acid (LTA), to activate phagocytic function in a concentration-dependent manner. Antibiotics have been shown to exert both direct antimicrobial action as well as immunomodulatory effects. In this study, we compared the effects of different anti-staphylococcal antibiotics on LTA-mediated immune activation of neutrophils. Methods Neutrophils obtained from healthy volunteers were exposed to two levels of LTA (1 and 10 μg/ml) with or without addition of antibiotics from different pharmacologic classes (vancomycin, daptomycin, ceftaroline). Neutrophil function was assessed by examining phagocytic response, activation (CD11b, CD62L expression), Toll-like receptor-2 expression, cell survival and apoptosis, and CXCL8 release. Results Differential LTA-mediated antibiotic effects on neutrophil function were observed primarily at the high LTA exposure level. Ceftaroline in the presence of 10 μg/ml LTA had the most prominent effects on phagocytosis and CD11b and CD62L expression, with trends towards increased neutrophil survival and preservation of CXCL8 release when compared to daptomycin and vancomycin with the latter significantly dampening PMN CXCL8 release. Conclusions Select antimicrobial agents, such as ceftaroline, exert immunostimulatory effects on neutrophils exposed to S. aureus LTA, which when confirmed in vivo, could be leveraged for its dual immunomodulatory and antibacterial actions for the treatment of persistent SAB mediated by a dysregulated host response.

scholarly journals EVALUATION OF IN VITRO CYTOTOXIC EFFECT OF VIOLACEIN PRODUCED BY NOVEL ISOLATE CHROMOBACTERIUM VACCINII CV5 AGAINST THE CERVICAL AND LUNG CANCER CELL

2017 ◽  
Vol 10 (10) ◽  
pp. 227 ◽  
Author(s):  
Vishnu T Santhosh ◽  
Palaniswamy Muthusamy
Keyword(s):  
Lung Cancer ◽  
Anticancer Activity ◽  
Cell Lines ◽  
Cancer Cell ◽  
A549 Cells ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Cytotoxicity Activity ◽  
Ic50 Values

  Objectives: This study investigates the in vitro anticancer activity of the violacein extracted from the Chromobacterium vaccinii CV5.Methods: Natural colorants or dyes derived from flora to fauna are believed to be safe because of nontoxic, noncarcinogenic, and biodegradable in nature. There are a number of natural pigments, but only a few are available in sufficient quantities for industrial production. The cytotoxicity activity of pigment was assessed against the cervical (HeLa) and lung cancer (A549) cell lines using the MTT assay and there by potential cytotoxic activity exhibited by the pigment was identified.Results: The result of the pigment shows potent anticancer activity on the two cancer cell lines tested in a concentration dependent manner. The potent anticancer activity was observed with the pigment with IC50 values of 26 μg/mL on HeLa and 31 μg/mL on A549 cells, respectively.Conclusion: The study is pioneering report for determining the better in vitro anticancer activity of violacein from the novel isolate C. vaccinii CV5.

scholarly journals Novel Anion Liposome-Encapsulated Antisense Oligonucleotide Restores Susceptibility of Methicillin-Resistant Staphylococcus aureus and Rescues Mice from Lethal Sepsis by Targeting mecA

2009 ◽  
Vol 53 (7) ◽  
pp. 2871-2878 ◽  
Author(s):  
Jingru Meng ◽  
Hui Wang ◽  
Zheng Hou ◽  
Tao Chen ◽  
Jingguo Fu ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Survival Rates ◽  
Treated Group ◽  
Antisense Oligodeoxynucleotide ◽  
Control Group ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Lethal Sepsis ◽  
Mueller Hinton Agar ◽  
Novel Strategy

ABSTRACT β-Lactam resistance in methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) is caused by the production of an additional low-affinity penicillin-binding protein 2a, which is encoded by the mecA gene. The disruption of mecA may inhibit mecA expression and thereafter lead to the restoration of MRSA susceptibility to β-lactams. In this study, we developed a novel anionic liposome for encapsulating and delivering the complexes of a specific anti-mecA phosphorothioate oligodeoxynucleotide (PS-ODN833) and polycation polyethylenimine (PEI). The efficiencies of liposome encapsulation of the complexes were around 79.7% ± 2.7%. The liposomes showed sustained release of PS-ODN833 at 37°C but very low levels of release at 4°C and room temperature. The addition of the encapsulated anti-mecA PS-ODN833-PEI complex to cultures of MRSA strains caused 45, 76, 82, and 93% reductions in mecA expression, accompanied by the inhibition of MRSA growth on Mueller-Hinton agar containing oxacillin (6 μg/ml) in a concentration-dependent manner. The encapsulated-PS-ODN833 treatment also reduced the MICs of five of the most commonly used antibiotics for MRSA clinical isolates to values within the sensitivity range and rescued mice from MRSA-caused septic death by downregulating mecA. The survival rates of septic mice increased from 0% for the control group to 53% for the PS-ODN833-treated group. The results were associated with reductions of bacterial titers in the blood of surviving mice. The findings of the present study indicate that an antisense oligodeoxynucleotide targeted to mecA can significantly restore the susceptibility of MRSA to existing β-lactam antibiotics, providing an apparently novel strategy for treating MRSA infections.

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