scholarly journals Cathelicidin Peptides Restrict Bacterial Growth via Membrane Perturbation and Induction of Reactive Oxygen Species

mBio ◽  
2019 ◽  
Vol 10 (5) ◽  
Author(s):  
Dean A. Rowe-Magnus ◽  
Adenine Y. Kao ◽  
Antonio Cembellin Prieto ◽  
Meng Pu ◽  
Cheng Kao
Keyword(s):  
Reactive Oxygen Species ◽  
Antimicrobial Peptides ◽  
Single Cell ◽  
Reactive Oxygen ◽  
Cellular Damage ◽  
Primary Effect ◽  
Gram Negative Bacteria ◽  
Oxygen Species ◽  
Gram Positive ◽  
Gram Negative

ABSTRACT All metazoans produce antimicrobial peptides (AMPs) that have both broad antimicrobial and immunomodulatory activity. Cathelicidins are AMPs that preferentially kill Gram-negative bacteria in vitro, purportedly by assembling into higher-order structures that perforate the membrane. We utilized high-resolution, single-cell fluorescence microscopy to examine their mechanism of action in real time. Engineered cathelicidins rapidly bound to Gram-negative and Gram-positive cells and penetrated the cytoplasmic membrane. Rapid failure of the peptidoglycan superstructure in regions of active turnover caused leakage of cytoplasmic contents and the formation of membrane-bound blebs. A mutation anticipated to destabilize interactions between cathelicidin subunits had no effect on bactericidal activity, suggesting that cathelicidins have activities beyond perforating the membrane. Nanomolar concentrations of cathelicidins, although not bactericidal, reduced the growth rate of Gram-negative and Gram-positive bacteria. The cells exhibited expression changes in multiple essential processes, including protein synthesis, peptidoglycan biosynthesis, respiration, and the detoxification of reactive oxygen species (ROS). Time-lapse imaging revealed that ROS accumulation preceded bleb formation, and treatments that reduced cellular ROS levels overcame these bactericidal effects. We propose that that the primary effect of cathelicidins is to induce the production of ROS that damage bacterial molecules, leading to slowed growth or cell death. Given their low circulating levels in vivo, AMPs may serve to slow bacterial population expansion so that cellular immunity systems can respond to and battle the infection. IMPORTANCE Antimicrobial peptides (AMPs) are an important part of the mammalian innate immune system in the battle against microbial infection. How AMPs function to control bacteria is not clear, as nearly all activity studies use nonphysiological levels of AMPs. We monitored peptide action in live bacterial cells over short time frames with single-cell resolution and found that the primary effect of cathelicidin peptides is to increase the production of oxidative molecules that cause cellular damage in Gram-positive and Gram-negative bacteria.

scholarly journals Salmonella Rapidly Regulates Membrane Permeability To Survive Oxidative Stress

mBio ◽  
2016 ◽  
Vol 7 (4) ◽  
Author(s):  
Joris van der Heijden ◽  
Lisa A. Reynolds ◽  
Wanyin Deng ◽  
Allan Mills ◽  
Roland Scholz ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Hydrogen Peroxide ◽  
Membrane Permeability ◽  
Outer Membrane ◽  
Reactive Oxygen ◽  
Gram Negative Bacteria ◽  
Oxygen Species ◽  
Bacterial Killing ◽  
Gram Negative

ABSTRACT The outer membrane (OM) of Gram-negative bacteria provides protection against toxic molecules, including reactive oxygen species (ROS). Decreased OM permeability can promote bacterial survival under harsh circumstances and protects against antibiotics. To better understand the regulation of OM permeability, we studied the real-time influx of hydrogen peroxide in Salmonella bacteria and discovered two novel mechanisms by which they rapidly control OM permeability. We found that pores in two major OM proteins, OmpA and OmpC, could be rapidly opened or closed when oxidative stress is encountered and that the underlying mechanisms rely on the formation of disulfide bonds in the periplasmic domain of OmpA and TrxA, respectively. Additionally, we found that a Salmonella mutant showing increased OM permeability was killed more effectively by treatment with antibiotics. Together, these results demonstrate that Gram-negative bacteria regulate the influx of ROS for defense against oxidative stress and reveal novel targets that can be therapeutically targeted to increase bacterial killing by conventional antibiotics. IMPORTANCE Pathogenic bacteria have evolved ways to circumvent inflammatory immune responses. A decrease in bacterial outer membrane permeability during infection helps protect bacteria from toxic molecules produced by the host immune system and allows for effective colonization of the host. In this report, we reveal molecular mechanisms that rapidly alter outer membrane pores and their permeability in response to hydrogen peroxide and oxidative stress. These mechanisms are the first examples of pores that are rapidly opened or closed in response to reactive oxygen species. Moreover, one of these mechanisms can be targeted to artificially increase membrane permeability and thereby increase bacterial killing by the antibiotic cefotaxime during in vitro experiments and in a mouse model of infection. We envision that a better understanding of the regulation of membrane permeability will lead to new targets and treatment options for multidrug-resistant infections.

scholarly journals Reactive Oxygen Species, Apoptosis, Antimicrobial Peptides and Human Inflammatory Diseases

2015 ◽  
Vol 8 (2) ◽  
pp. 151-175 ◽  
Author(s):  
Babatunji Oyinloye ◽  
Abiola Adenowo ◽  
Abidemi Kappo
Keyword(s):  
Reactive Oxygen Species ◽  
Antimicrobial Peptides ◽  
Inflammatory Diseases ◽  
Reactive Oxygen ◽  
Oxygen Species

Generation of Reactive Oxygen Species by Quartz Particles and Its Implication for Cellular Damage

1995 ◽  
Vol 10 (12) ◽  
pp. 1138-1144 ◽  
Author(s):  
Xianglin Shi ◽  
Yan Mao ◽  
Lambert N. Danie ◽  
Umberto Saffiotti ◽  
Nar S. Dalal ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Reactive Oxygen ◽  
Cellular Damage ◽  
Oxygen Species

The Maillard reaction of a shrimp by-product protein hydrolysate: chemical changes and inhibiting effects of reactive oxygen species in human HepG2 cells

2015 ◽  
Vol 6 (6) ◽  
pp. 1919-1927 ◽  
Author(s):  
Fengchao Zha ◽  
Binbin Wei ◽  
Shengjun Chen ◽  
Shiyuan Dong ◽  
Mingyong Zeng ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Maillard Reaction ◽  
Hepg2 Cells ◽  
Nutritional Quality ◽  
Protein Hydrolysate ◽  
Reactive Oxygen ◽  
Cellular Damage ◽  
Oxygen Species ◽  
Chemical Changes

A shrimp by-product protein hydrolysate via the Maillard reaction could alleviate cellular damage, but result in higher HMF and loss of nutritional quality.

scholarly journals Photodynamic Effects of Novel XF Porphyrin Derivatives on Prokaryotic and Eukaryotic Cells

2005 ◽  
Vol 49 (4) ◽  
pp. 1542-1552 ◽  
Author(s):  
T. Maisch ◽  
C. Bosl ◽  
R.-M. Szeimies ◽  
N. Lehn ◽  
C. Abels
Keyword(s):  
Reactive Oxygen Species ◽  
Antibiotic Resistance ◽  
Reactive Oxygen ◽  
Human Keratinocytes ◽  
Eukaryotic Cells ◽  
Resistance Pattern ◽  
Resistant Bacteria ◽  
Oxygen Species ◽  
Gram Positive ◽  
Methicillin Resistant

ABSTRACT The worldwide rise in the rates of antibiotic resistance of bacteria underlines the need for alternative antibacterial agents. A promising approach to the killing of gram-positive antibiotic-resistant bacteria of the skin uses light in combination with a photosensitizer to induce a phototoxic reaction. Different concentrations (0 to 100 μM) of porphyrin-based photosensitizers (CTP1, XF70, and XF73) and different incubation times (5 min, 1 h, and 4 h) were used to determine phototoxicity against two methicillin-resistant Staphylococcus aureus strains, one methicillin-sensitive S. aureus strain, one methicillin-resistant Staphylococcus epidermidis strain, one Escherichia coli strain, and human keratinocytes and fibroblasts. Incubation with 0.005 μM XF70 or XF73, followed by illumination, yielded a 3-log10 (≥99.9%) decrease in the viable cell numbers of all staphylococcal strains, indicating that the XF drugs have high degrees of potency against gram-positive bacteria and also that the activities of these novel drugs are independent of the antibiotic resistance pattern of the staphylococci examined. CTP1 was less potent against the staphylococci under the same conditions. At 0.005 μM, XF70 and XF73 demonstrated no toxicity toward fibroblasts or keratinocytes. No inactivation of E. coli was detected at this concentration. XF73 was confirmed to act via a reactive oxygen species from the results of studies with sodium azide (a quencher of singlet oxygen), which reduced the killing of both eukaryotic and prokaryotic cells. When a quencher of superoxide anion and the hydroxyl radical was used, cell killing was not inhibited. These results demonstrate that the porphyrin-based photosensitizers had concentration-dependent differences in their efficacies of killing of methicillin-resistant staphylococcal strains via reactive oxygen species without harming eukaryotic cells at the same concentrations.

scholarly journals Exposure to C. Albicans Makes Bladder Epithelial Cells Induce Apoptosis and Modification of Their Microenvironment

2021 ◽  
Author(s):  
Jayoung Kim ◽  
Austin Yeon ◽  
Khandakar Tanvir Ahmed ◽  
Wei Zhang ◽  
Khae-Hawn Kim ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Epithelial Cells ◽  
Western Blot ◽  
Growth Factor Receptor ◽  
Reactive Oxygen ◽  
Cellular Damage ◽  
Signal Pathways ◽  
Oxygen Species ◽  
Bladder Pain ◽  
Normal Bladder

Abstract INTRODUCTION. Interstitial cystitis/painful bladder syndrome (IC) is characterized by chronic bladder pain and urinary storage symptoms. IC affects more than 3.3 million women in the U.S. alone. Ibis T-5000 assays and next generation sequencing have revealed that the C. albicans fungus is highly abundant in the urine of IC patients, particularly those who report greater pain, urinary urgency, and flares. However, currently, the clinical significance of C. albicans in the urine remains elusive. Here, we report the pathological effects and mechanisms triggered by C. albicans in a healthy normal bladder. METHODS. Immortalized bladder epithelial cells were infected with C. albicans. Perturbations in gene expression were identified using an Affymetrix gene microarray and subsequently followed with bioinformatic analyses, including gene set enrichment. Inflammatory and apoptotic genes were quantified using RT-PCR and Western blot analyses. Central signal pathways were examined using Western blot analysis. RESULTS. DNA microarray analysis showed alterations in the transcriptome of bladder epithelial cells infected with C. albicans over both the short and long terms. Key inflammatory and apoptosis networks were changed, which was consistent with several cellular events. Cellular levels of reactive oxygen species and nitrogen oxide increased after infection. Productions of cyclooxygenase-2 and prostaglandine E2 also increased after C. albicans infection, and their productions were suppressed by blockage of reactive oxygen species-epidermal growth factor receptor-Erk pathway. CONCLUSIONS. This study provides evidence that C. albicans infection triggers inflammation and cellular damage by dysregulating key regulatory genes, signaling pathways, and bioactive species in normal bladder cells.

scholarly journals Antibiotic Korormicin A Kills Bacteria by Producing Reactive Oxygen Species

2019 ◽  
Vol 201 (11) ◽  
Author(s):  
Adam Maynard ◽  
Nicole L. Butler ◽  
Takeshi Ito ◽  
Adilson José da Silva ◽  
Masatoshi Murai ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Pseudomonas Aeruginosa ◽  
Vibrio Cholerae ◽  
Pathogenic Bacteria ◽  
Reactive Oxygen ◽  
Direct Result ◽  
Oxygen Species ◽  
Gram Negative ◽  
Content Type ◽  
Nadh:Quinone Oxidoreductase

ABSTRACT Korormicin is an antibiotic produced by some pseudoalteromonads which selectively kills Gram-negative bacteria that express the Na+-pumping NADH:quinone oxidoreductase (Na+-NQR.) We show that although korormicin is an inhibitor of Na+-NQR, the antibiotic action is not a direct result of inhibiting enzyme activity. Instead, perturbation of electron transfer inside the enzyme promotes a reaction between O2 and one or more redox cofactors in the enzyme (likely the flavin adenine dinucleotide [FAD] and 2Fe-2S center), leading to the production of reactive oxygen species (ROS). All Pseudoalteromonas contain the nqr operon in their genomes, including Pseudoalteromonas strain J010, which produces korormicin. We present activity data indicating that this strain expresses an active Na+-NQR and that this enzyme is not susceptible to korormicin inhibition. On the basis of our DNA sequence data, we show that the Na+-NQR of Pseudoalteromonas J010 carries an amino acid substitution (NqrB-G141A; Vibrio cholerae numbering) that in other Na+-NQRs confers resistance against korormicin. This is likely the reason that a functional Na+-NQR is able to exist in a bacterium that produces a compound that typically inhibits this enzyme and causes cell death. Korormicin is an effective antibiotic against such pathogens as Vibrio cholerae, Aliivibrio fischeri, and Pseudomonas aeruginosa but has no effect on Bacteroides fragilis and Bacteroides thetaiotaomicron, microorganisms that are important members of the human intestinal microflora. IMPORTANCE As multidrug antibiotic resistance in pathogenic bacteria continues to rise, there is a critical need for novel antimicrobial agents. An essential requirement for a useful antibiotic is that it selectively targets bacteria without significant effects on the eukaryotic hosts. Korormicin is an excellent candidate in this respect because it targets a unique respiratory enzyme found only in prokaryotes, the Na+-pumping NADH:quinone oxidoreductase (Na+-NQR). Korormicin is synthesized by some species of the marine bacterium Pseudoalteromonas and is a potent and specific inhibitor of Na+-NQR, an enzyme that is essential for the survival and proliferation of many Gram-negative human pathogens, including Vibrio cholerae and Pseudomonas aeruginosa, among others. Here, we identified how korormicin selectively kills these bacteria. The binding of korormicin to Na+-NQR promotes the formation of reactive oxygen species generated by the reaction of the FAD and the 2Fe-2S center cofactors with O2.

scholarly journals Antibacterial Peptides

Antibiotics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 142
Author(s):  
Jean-Marc Sabatier
Keyword(s):  
Antimicrobial Peptides ◽  
Host Defense ◽  
Life Forms ◽  
Natural Host ◽  
Gram Negative Bacteria ◽  
Antibacterial Peptides ◽  
Chemotherapeutic Drugs ◽  
Gram Positive ◽  
Defense Compounds ◽  
Gram Negative

As natural host defense compounds produced by numerous prokaryotic and eukaryotic life forms, antimicrobial peptides (AMPs) are now emerging as solid candidate chemotherapeutic drugs to fight against the various types of pathogenic Gram-positive and Gram-negative bacteria, especially those resistant to current antibiotics [...]

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