scholarly journals Antivirulence Properties of a Low-Molecular-Weight Quaternized Chitosan Derivative against Pseudomonas aeruginosa

2021 ◽  
Vol 9 (5) ◽  
pp. 912
Author(s):  
Giuseppantonio Maisetta ◽  
Anna Maria Piras ◽  
Vincenzo Motta ◽  
Simona Braccini ◽  
Diletta Mazzantini ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Pseudomonas Aeruginosa ◽  
Virulence Factors ◽  
Intracellular Localization ◽  
Confocal Scanning Laser Microscopy ◽  
Low Molecular Weight ◽  
Antibiofilm Activity ◽  
Synergistic Activity ◽  
Chitosan Derivative ◽  
Quaternized Chitosan

The co-occurrence of increasing rates of resistance to current antibiotics and the paucity of novel antibiotics pose major challenges for the treatment of bacterial infections. In this scenario, treatments targeting bacterial virulence have gained considerable interest as they are expected to exert a weaker selection for resistance than conventional antibiotics. In a previous study, we demonstrated that a low-molecular-weight quaternized chitosan derivative, named QAL, displays antibiofilm activity against the major pathogen Pseudomonas aeruginosa at subinhibitory concentrations. The aim of this study was to investigate whether QAL was able to inhibit the production of relevant virulence factors of P. aeruginosa. When tested in vitro at subinhibiting concentrations (0.31–0.62 mg/mL), QAL markedly reduced the production of pyocyanin, pyoverdin, proteases, and LasA, as well as inhibited the swarming motility of three out of four P. aeruginosa strains tested. Furthermore, quantitative reverse transcription PCR (qRT-PCR) analyses demonstrated that expression of lasI and rhlI, two QS-related genes, was highly downregulated in a representative P. aeruginosa strain. Confocal scanning laser microscopy analysis suggested that FITC-labelled QAL accumulates intracellularly following incubation with P. aeruginosa. In contrast, the reduced production of virulence factors was not evidenced when QAL was used as the main polymeric component of polyelectrolyte-based nanoparticles. Additionally, combination of sub-MIC concentrations of QAL and tobramycin significantly reduced biofilm formation of P. aeruginosa, likely due to a synergistic activity towards planktonic bacteria. Overall, the results obtained demonstrated an antivirulence activity of QAL, possibly due to polymer intracellular localization and QS-inhibition, and its ability to inhibit P. aeruginosa growth synergizing with tobramycin.

scholarly journals Low-Molecular-Weight Metabolites Secreted by Paenibacillus larvae as Potential Virulence Factors of American Foulbrood

2014 ◽  
Vol 80 (8) ◽  
pp. 2484-2492 ◽  
Author(s):  
Hedwig-Annabell Schild ◽  
Sebastian W. Fuchs ◽  
Helge B. Bode ◽  
Bernd Grünewald
Keyword(s):  
Molecular Weight ◽  
Virulence Factors ◽  
Gene Clusters ◽  
Paenibacillus Larvae ◽  
Economic Losses ◽  
Low Molecular Weight ◽  
American Foulbrood ◽  
Toxic Activity ◽  
Content Type

ABSTRACTThe spore-forming bacteriumPaenibacillus larvaecauses a severe and highly infective bee disease, American foulbrood (AFB). Despite the large economic losses induced by AFB, the virulence factors produced byP. larvaeare as yet unknown. To identify such virulence factors, we experimentally infected young, susceptible larvae of the honeybee,Apis mellifera carnica, with differentP. larvaeisolates. Honeybee larvae were rearedin vitroin 24-well plates in the laboratory after isolation from the brood comb. We identified genotype-specific differences in the etiopathology of AFB between the tested isolates ofP. larvae, which were revealed by differences in the median lethal times. Furthermore, we confirmed that extracts ofP. larvaecultures contain low-molecular-weight compounds, which are toxic to honeybee larvae. Our data indicate thatP. larvaesecretes metabolites into the medium with a potent honeybee toxic activity pointing to a novel pathogenic factor(s) ofP. larvae. Genome mining ofP. larvaesubsp.larvaeBRL-230010 led to the identification of several biosynthesis gene clusters putatively involved in natural product biosynthesis, highlighting the potential ofP. larvaeto produce such compounds.

scholarly journals Bacterial surfactants as agents with antibiofilm activity

2021 ◽  
Vol 16 (1) ◽  
pp. 94-104
Author(s):  
А.Е. Abaturov
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Low Molecular Weight ◽  
Antibiofilm Activity ◽  
Antibiotic Resistant ◽  
Biological Surface ◽  
The Matrix ◽  
Surface Active ◽  
Bacteria And Fungi ◽  
Surface Active Compounds

Biosuragents are a heterogeneous group of biological surface-active amphiphilic compounds. The producers of biosurfactants are various microorganisms: bacteria and fungi. The class of biosurfactants consists of two groups: low molecular weight and high molecular weight compounds. Representatives of low molecular weight compounds are lipopeptides, glycolipids, fatty acids, phospholipids that reduce surface and interfacial tension, and high molecular weight compounds are polymer and dispersed biosurfactants, which are emulsion stabilizers. The most studied biosurfactants with the potential of drugs are lipopeptides and glycolipids. A subgroup of lipopeptides are polymyxins, pseudo-factins, putisolvins, surfactin, fengycin and others; and glycoli­pids — rhamnolipids, trehalose, sophorose, cellobiose, mannosileritritol lipids, and others. Biosurfactants play a key role in the life of biofilms: they regulate the adhesion of bacteria and biofilm matrix, support the functioning of the matrix channels, providing the nutrient needs of bacteria. It has also been shown that biosurfactants are involved in the formation and dispersion of formed biofilms. These substances, directly reacting with the components of the matrix, induce degradation of the biofilm. Biosurfing agents, possessing antimicrobial, antifungal and antiviral, and antitumor properties, are a promising class of compounds that, possessing a combination of antibacterial and antibiofilm action, open up new perspectives in the treatment of recurrent chronic infectious di­seases. It is believed that surface-active compounds, both representatives of lipopeptides and glycolipids, can be the molecular basis for the development of drugs that will enhance the effectiveness of antibiotic therapy for problem infections, especially those caused by antibiotic-resistant strains.

scholarly journals Immunovisualization of high (HK) and low (LK) molecular weight kininogens on isolated human neutrophils

Blood ◽  
1992 ◽  
Vol 79 (3) ◽  
pp. 754-759
Author(s):  
CD Figueroa ◽  
LM Henderson ◽  
J Kaufmann ◽  
RA De La Cadena ◽  
RW Colman ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cellular Localization ◽  
Confocal Scanning Laser Microscopy ◽  
Human Neutrophils ◽  
Low Molecular Weight ◽  
High Molecular Weight Kininogen ◽  
Confocal Scanning ◽  
Silver Staining Method ◽  
Confocal Scanning Laser

An immunocytochemical study was performed to examine the cellular localization and the subcellular distribution of kininogens in human blood cells. Kininogens were visualised using the immunogold-silver staining method and confocal scanning laser microscopy. We confirmed the existence of high molecular weight kininogen in human neutrophils and describe for the first time the presence of low molecular weight kininogen on these cells. Both high and low molecular weight kininogens were restricted to the neutrophils where they localized as clusters of immunogold particles on the cell membrane. No labeling was observed intracellularly in organelles such as mitochondria, endoplasmic reticulum, and azurophilic or specific granules after permeabilization of the neutrophils with Triton X-100, a procedure that permitted the visualization of elastase in the azurophilic granules. Clusters of high molecular weight kininogen molecules attached to the neutrophil surface could serve as receptors for plasma kallikrein and/or be the source of substrate for a discrete and circumscribed formation of kinins that may in turn facilitate the local diapedesis of neutrophils and the transudation of plasma constituents during acute inflammation.

scholarly journals Preparation, Structural Characterization, and Property Investigation of Gallic Acid-Grafted Fungal Chitosan Conjugate

2021 ◽  
Vol 7 (10) ◽  
pp. 812
Author(s):  
Weslley Souza de Paiva ◽  
Moacir Fernandes Queiroz ◽  
Diego Araujo Sabry ◽  
André Luiz Cabral Monteiro de Azevedo Santiago ◽  
Guilherme Lanzi Sassaki ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Molecular Weight ◽  
Gallic Acid ◽  
Low Molecular Weight ◽  
Fibroblast Cells ◽  
Chitosan Derivative ◽  
Promising Agent ◽  
Fungal Chitosan ◽  
Total Antioxidant

Oxidative stress is the cause of numerous diseases in humans; therefore, there has been a continuous search for novel antioxidant molecules. Fungal chitosan is an attractive molecule that has several applications (antifungal, antibacterial, anticancer and antiparasitic action) owing to its unique characteristics; however, it exhibits low antioxidant activity. The aim of this study was to obtain fungal chitosan (Chit-F) from the fungus Rhizopus arrhizus and synthesize its derivative, fungal chitosan-gallic acid (Chit-FGal), as a novel antioxidant chitosan derivative for biomedical use. A low molecular weight Chi-F (~3.0 kDa) with a degree of deacetylation of 86% was obtained from this fungus. Chit-FGal (3.0 kDa) was synthesized by an efficient free radical-mediated method using hydrogen peroxide (H2O2) and ascorbic acid. Both Chit-F and Chit-FGal showed similar copper chelating activities; however, Chit-FGal was more efficient as an antioxidant, exhibiting twice the total antioxidant capacity than Chi-F (p < 0.05). Furthermore, H2O2 (0.06 M) promoted a 50% decrease in the viabilities of the 3T3 fibroblast cells. However, this effect was abolished in the presence of Chit-FGal (0.05–0.25 mg/mL), indicating that Chit-FGal protected the cells from oxidative damage. These results suggest that Chit-FGal may be a promising agent to combat oxidative stress.

scholarly journals Copper and Quaternary Ammonium Cations Exert Synergistic Bactericidal and Antibiofilm Activity against Pseudomonas aeruginosa

2008 ◽  
Vol 52 (8) ◽  
pp. 2870-2881 ◽  
Author(s):  
Joe J. Harrison ◽  
Raymond J. Turner ◽  
Daniel A. Joo ◽  
Michelle A. Stan ◽  
Catherine S. Chan ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quaternary Ammonium ◽  
Cetylpyridinium Chloride ◽  
Single Agent ◽  
Titration Calorimetry ◽  
Antibiofilm Activity ◽  
Synergistic Activity ◽  
Chronic Infections ◽  
Biofilm Growth ◽  
Antimicrobial Treatments

ABSTRACT Biofilms are slimy aggregates of microbes that are likely responsible for many chronic infections as well as for contamination of clinical and industrial environments. Pseudomonas aeruginosa is a prevalent hospital pathogen that is well known for its ability to form biofilms that are recalcitrant to many different antimicrobial treatments. We have devised a high-throughput method for testing combinations of antimicrobials for synergistic activity against biofilms, including those formed by P. aeruginosa. This approach was used to look for changes in biofilm susceptibility to various biocides when these agents were combined with metal ions. This process identified that Cu2+ works synergistically with quaternary ammonium compounds (QACs; specifically benzalkonium chloride, cetalkonium chloride, cetylpyridinium chloride, myristalkonium chloride, and Polycide) to kill P. aeruginosa biofilms. In some cases, adding Cu2+ to QACs resulted in a 128-fold decrease in the biofilm minimum bactericidal concentration compared to that for single-agent treatments. In combination, these agents retained broad-spectrum antimicrobial activity that also eradicated biofilms of Escherichia coli, Staphylococcus aureus, Salmonella enterica serovar Cholerasuis, and Pseudomonas fluorescens. To investigate the mechanism of action, isothermal titration calorimetry was used to show that Cu2+ and QACs do not interact in aqueous solutions, suggesting that each agent exerts microbiological toxicity through independent biochemical routes. Additionally, Cu2+ and QACs, both alone and in combination, reduced the activity of nitrate reductases, which are enzymes that are important for normal biofilm growth. Collectively, the results of this study indicate that Cu2+ and QACs are effective combinations of antimicrobials that may be used to kill bacterial biofilms.

LOW MOLECULAR WEIGHT INTRACELLULAR IODOCOMPOUNDS WITH LONG INTRATHYROIDAL HALF-LIFE: REMNANTS OF THYROGLOBULIN HYDROLYSIS?

1979 ◽  
Vol 92 (1) ◽  
pp. 105-118 ◽  
Author(s):  
A. Haeberli ◽  
H. Engler ◽  
C. von Grünigen ◽  
H. Kohler ◽  
H. Studer
Keyword(s):  
Molecular Weight ◽  
Half Life ◽  
Intracellular Localization ◽  
Iodine Intake ◽  
Published Data ◽  
Low Molecular Weight ◽  
Total Iodine ◽  
Hydrolysis Of

ABSTRACT in this paper additional information on low molecular weight, soluble, intrathyroidal iodocompounds with slow metabolic rate is provided. These compounds have previously been localized autoradiographically within the follicular cells. Radioiodide was administered to rats on a normal iodine intake (6–7 μg/day) for 80 days to approach isotopic equilibration of the intrathyroidal iodine with the dietary radioiodide. When the isotope was omitted from the diet the intrathyroidal radioiodine was released with an apparent half-life of approximately 12 days. When the individual soluble components carrying radioiodine were analyzed after separation on Sephadex G-200, different apparent half-lives were found, the half-life of thyroglobulin (Tgb) being roughly 10 days and that of the low molecular weight iodocomounds being in the order of 60 to 100 days or more. In addition to the soluble low molecular weight iodocompounds, the radioactivity in the particulate fraction increased by 100 % during the tracer washout when compared to Tgb and the total soluble fraction. The soluble slow turnover iodocompounds contained a higher percentage of carbohydrate and total iodine than Tgb, while the relative amounts of each sugar analyzed (hexoses, fucose, hexosamine and sialic acid) were close to those in Tgb. Sephadex G-25 chromatography of the low molecular weight iodocompounds obtained after Sephadex G-200 separation resulted in the separation of 4 peaks. Two peaks identified as iodopeptides could be further analyzed. The carbohydrate composition of these peptides was similar to that of 2 glycopeptides obtained after in vitro enzymatic hydrolysis of purified Tgb with pronase. Slow equilibration with radioiodine, long apparent intrathyroidal half-life and carbohydrate content similar to that of Tgb, taken together with previously published data on intracellular localization of soluble intrathyroidal iodocompounds, suggest that the low molecular weight iodocompounds are products of in vivo hydrolysis of engulfed Tgb droplets.

scholarly journals Immunovisualization of high (HK) and low (LK) molecular weight kininogens on isolated human neutrophils

Blood ◽  
1992 ◽  
Vol 79 (3) ◽  
pp. 754-759 ◽  
Author(s):  
CD Figueroa ◽  
LM Henderson ◽  
J Kaufmann ◽  
RA De La Cadena ◽  
RW Colman ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cellular Localization ◽  
Confocal Scanning Laser Microscopy ◽  
Human Neutrophils ◽  
Low Molecular Weight ◽  
High Molecular Weight Kininogen ◽  
Confocal Scanning ◽  
Silver Staining Method ◽  
Confocal Scanning Laser

Abstract An immunocytochemical study was performed to examine the cellular localization and the subcellular distribution of kininogens in human blood cells. Kininogens were visualised using the immunogold-silver staining method and confocal scanning laser microscopy. We confirmed the existence of high molecular weight kininogen in human neutrophils and describe for the first time the presence of low molecular weight kininogen on these cells. Both high and low molecular weight kininogens were restricted to the neutrophils where they localized as clusters of immunogold particles on the cell membrane. No labeling was observed intracellularly in organelles such as mitochondria, endoplasmic reticulum, and azurophilic or specific granules after permeabilization of the neutrophils with Triton X-100, a procedure that permitted the visualization of elastase in the azurophilic granules. Clusters of high molecular weight kininogen molecules attached to the neutrophil surface could serve as receptors for plasma kallikrein and/or be the source of substrate for a discrete and circumscribed formation of kinins that may in turn facilitate the local diapedesis of neutrophils and the transudation of plasma constituents during acute inflammation.

scholarly journals ADP-Ribosylation of Rab5 by ExoS ofPseudomonas aeruginosa Affects Endocytosis

2001 ◽  
Vol 69 (9) ◽  
pp. 5329-5334 ◽  
Author(s):  
Alejandro M. Barbieri ◽  
Qun Sha ◽  
Pascale Bette-Bobillo ◽  
Philip D. Stahl ◽  
Michel Vidal
Keyword(s):  
Molecular Weight ◽  
Pseudomonas Aeruginosa ◽  
Horseradish Peroxidase ◽  
Marked Decrease ◽  
Low Molecular Weight ◽  
Strong Inhibition ◽  
Exoenzyme S ◽  
Adp Ribosylation ◽  
Adp Ribosyltransferase ◽  
Stimulation Of

ABSTRACT Pseudomonas aeruginosa exoenzyme S (ExoS) is an ADP-ribosyltransferase that modifies low-molecular-weight GTPases. Here we studied the effect of Rab5 ADP-ribosylation by ExoS on its cellular function, i.e., regulation of early endocytic events. Coculture of CHO cells with P. aeruginosa induced a marked decrease in horseradish peroxidase (HRP) uptake compared to noninfected cells, while coculture with a P. aeruginosa mutant strain that fails to produce ExoS did not lead to any change in HRP uptake. Microinjection of recombinant ExoS into Xenopus oocytes induced strong inhibition of basal HRP uptake by oocytes. Moreover, coinjection of recombinant ExoS with Rab5 abolished the typical stimulation of HRP uptake obtained after GTPase microinjection. Cytosols prepared from injected oocytes were used in an endosome-endosome fusion assay. Cytosol from ExoS-microinjected oocytes was ineffective in promoting endosome-endosome fusion. However, in these conditions, the addition of Rab5 to the assay led to fusion recovery. Finally, we found that the interaction of Rab5 with EEA1 was markedly diminished after Rab5 ADP-ribosylation by ExoS.

scholarly journals Iron Acquisition from Pseudomonas aeruginosa Siderophores by Human Phagocytes: an Additional Mechanism of Host Defense through Iron Sequestration?

2000 ◽  
Vol 68 (3) ◽  
pp. 1271-1275 ◽  
Author(s):  
Bradley E. Britigan ◽  
George T. Rasmussen ◽  
Oyebode Olakanmi ◽  
Charles D. Cox
Keyword(s):  
Molecular Weight ◽  
Pseudomonas Aeruginosa ◽  
Host Defense ◽  
Iron Acquisition ◽  
High Capacity ◽  
Human Neutrophils ◽  
Low Molecular Weight ◽  
Additional Mechanism ◽  
Low Molecular Weight Iron

ABSTRACT Chelation of iron to iron-binding proteins is a strategy of host defense. Some pathogens counter this via the secretion of low-molecular-weight iron-chelating agents (siderophores). Human phagocytes possess a high-capacity mechanism for iron acquisition from low-molecular-weight iron chelates. Efficient acquisition and sequestration of iron bound to bacterial siderophores by host phagocytes could provide a secondary mechanism to limit microbial access to iron. In the present work we report that human neutrophils, macrophages, and myeloid cell lines can acquire iron from the twoPseudomonas aeruginosa siderophores. Analogous to iron acquisition from other low-molecular-weight chelates, iron acquisition from the siderophores is ATP independent, induced by multivalent cationic metals, and unaffected by inhibitors of endocytosis and pinocytosis. In vivo, this process could serve as an additional mechanism of host defense to limit iron availability to invading siderophore-producing microbes.

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