Internalization of Staphylococcus aureus in lymphocytes induces oxidative stress and DNA fragmentation: possible ameliorative role of nanoconjugated vancomycin

A review on oxidant and antioxidant effects of antibacterial agents: impacts on bacterial cell death and division and therapeutic effects or adverse reactions in humans

Reactive oxygen species (ROS) are produced in the mitochondrial respiratory pathway and cellular metabolism. They are responsible for creating oxidative stress and lipid peroxidation. In living organisms, there is a balance between oxidative stress and the antioxidant system, but some factors such as medicines disturb the balance and cause many problems. These effects can impact bacterial death and division and also in humans can induce therapeutic or adverse reactions. Web of Science and Pubmed databases were used for searching. This review focuses on the oxidant and antioxidant effects of different classes of antibacterial agents and the mechanisms of oxidative stress. Some of these agents have beneficial effects on killing bacteria due to their antioxidant or oxidant effects. However, some of their side effects may be due to their oxidative effects. Based on the results of this review, minocycline is an antioxidant, but aminoglycosides, chloramphenicol, glycopeptides, antituberculosis drugs, fluoroquinolones, and sulfamethoxazole agents have oxidant effects. Furthermore, cephalosporins, penicillins, metronidazole, and macrolides have both oxidant and antioxidant effects in different studies. It is concluded that some antibacterial agents have oxidant and other antioxidant effects. These activities may affect their therapeutic effects or side effects. Some antioxidants can prevent the adverse effects of antibacterial agents. Clarifying the exact oxidant and antioxidant effects of some antimicrobial agents needs more research projects.

The Application of Nucleic Acids and Nucleic Acid Materials in Antimicrobial Research

Due to the misuse of antibiotics, multiple drug-resistant pathogenic bacteria have increasingly emerged. This has increased the difficulty of treatment as these bacteria directly affect public health by diminishing the potency of existing antibiotics. Developing alternative therapeutic strategies is the urgent need to reduce the mortality and morbidity related to drug-resistant bacterial infections. In the past 10 to 20 years, nanomedicines have been widely studied and applied as an antibacterial agent. They have become a novel tool for fighting resistant bacteria. The most common innovative substances, metal and metal oxide nanoparticles (NPs), have been widely reported. Until recently, DNA nanostructures were used alone or functionalized with specific DNA sequences by many scholars for antimicrobial purposes which were alternatively selected as therapy for severe bacterial infections. These are a potential candidate for treatments and have a considerable role in killing antibiotic-resistant bacteria. This review involves the dimensions of multidrug resistance and the mechanism of bacteria developing drug resistance. The importance of this article is that we summarized the current study of nano-materials based on nucleic acids in antimicrobial use. Meanwhile, the current progress and the present obstacles for their antibacterial and therapeutic use and special function of stem cells in this field are also discussed.

Vancomycin-Induced Kidney Injury: Animal Models of Toxicodynamics, Mechanisms of Injury, Human Translation, and Potential Strategies for Prevention

Vancomycin is a recommended therapy in multiple national guidelines. Despite the common use, there is a poor understanding of the mechanistic drivers and potential modifiers of vancomycin-mediated kidney injury. In this review, historic and contemporary rates of vancomycin-induced kidney injury (VIKI) are described, and toxicodynamic models and mechanisms of toxicity from preclinical studies are reviewed. Aside from known clinical covariates that worsen VIKI, preclinical models have demonstrated that various factors impact VIKI, including dose, route of administration, and thresholds for pharmacokinetic parameters. The degree of acute kidney injury (AKI) is greatest with the intravenous route and higher doses that produce larger maximal concentrations and areas under the concentration curve. Troughs (i.e., minimum concentrations) have less of an impact. Mechanistically, preclinical studies have identified that VIKI is a result of drug accumulation in proximal tubule cells, which triggers cellular oxidative stress and apoptosis. Yet, there are several gaps in the knowledge that may represent viable targets to make vancomycin therapy less toxic. Potential strategies include prolonging infusions and lowering maximal concentrations, administration of antioxidants, administering agents that decrease cellular accumulation, and reformulating vancomycin to alter the renal clearance mechanism. Based on preclinical models and mechanisms of toxicity, we propose potential strategies to lessen VIKI.

Herbal medicines to the treatment of skin and soft tissue infections: advantages of the multi-targets action

The research for new treatments of skin and soft tissue infections (SSTIs) is important due to their high prevalence and number of hospitalizations. The purpose of this review is to address the pathophysiology of SSTIs to highlight the advantages of herbal medicines to their treatment, showing examples of species and compounds with multi-targets action. SSTIs have a complex physiopathology involving the microorganism, as well as inflammation and difficult healing. Therefore, antimicrobial, anti-inflammatory, antioxidant and healing activities are an approach possible for their treatment. Herbal medicines have a wide diversity of biological compounds, mainly phenolic compounds that may act on different targets and also have synergism between them. Therefore, a single medicine may have the four key activities that allied allow eliminating the infection, control the inflammation process and accelerating the healing process, preventing complications with chronic infections.

Biodistribution and toxickinetic variances of chemical and green Copper oxide nanoparticles in vitro and in vivo

In this study, chemical (S1) and green (S2) Copper Oxide nanoparticles (NPs) were synthesized to determine their biodistribution and toxicokinetic variances in vitro and in vivo. Both NPs significantly released Copper ions (Cu) in lymphocytes and were primarily deposited in the mononuclear phagocyte system (MPS) such as the liver and spleen in mice. In particular, S2NPs seemed to be prominently stored in the spleen, whereas the S1NPs were widely stored in more organs including the liver, heart, lungs, kidney and intestine. The circulation in the blood and fecal excretions both showed higher S2NPs contents respectively. Measurements of cell viability, Hemolysis assay, Reactive Oxygen Species (ROS) generation, biochemical estimation and apoptotic or necrotic study in lymphocytes after 24 h and measurements of body and organ weight, serum chemistry evaluation, cytokines level, protein expressions and histopathology of Balb/C mice after 15 days indicated significant toxicity difference between the S1NPs and S2NPs. Our observations proved that the NPs physiochemical properties influence toxicity and Biodistribution profiles in vitro and in vivo.

Bactericidal activity of curcumin I is associated with damaging of bacterial membrane

Curcumin, an important constituent of turmeric, is known for various biological activities, primarily due to its antioxidant mechanism. The present study focused on the antibacterial activity of curcumin I, a significant component of commercial curcumin, against four genera of bacteria, including those that are Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa). These represent prominent human pathogens, particularly in hospital settings. Our study shows the strong antibacterial potential of curcumin I against all the tested bacteria from Gram-positive as well as Gram-negative groups. The integrity of the bacterial membrane was checked using two differential permeabilization indicating fluorescent probes, namely, propidium iodide and calcein. Both the membrane permeabilization assays confirmed membrane leakage in Gram-negative and Gram-positive bacteria on exposure to curcumin I. In addition, scanning electron microscopy and fluorescence microscopy were employed to confirm the membrane damages in bacterial cells on exposure to curcumin I. The present study confirms the broad-spectrum antibacterial nature of curcumin I, and its membrane damaging property. Findings from this study could provide impetus for further research on curcumin I regarding its antibiotic potential against rapidly emerging bacterial pathogens.

In vitro Staphylococcus aureus-induced oxidative stress in mice murine peritoneal macrophages: a duration-dependent approach

OBJECTIVE

To evaluate the free radical generation and status of the antioxidant enzymes in murine peritoneal macrophage during in vitro vancomycin sensitive Staphylococcus aureus (VSSA) treatment with different time interval.

METHODS

Peritoneal macrophages were treated with 5×10(6) CFU/mL VSSA cell suspension in vitro for different time interval (1, 2, 3, 6, 12, and 24 h) and superoxide anion generation, NADPH oxidase activity, myeloperoxidase activity, nitric oxide generation, antioxidant enzyme status and components of glutathione cycle were analyzed.

RESULTS

Superoxide anion generation, NADPH oxidase activity, myeloperoxidase activity and nitric oxide generation got peak at 3 h, indicating maximum free radical generation through activation of NADPH oxidase in murine peritoneal macrophages during VSSA infection. Reduced glutathione level, glutathione peroxidase, glutathione reductase, and glutathione-s-transferase activity were decreased significantly (P<0.05) with increasing time of VSSA infection. But the oxidized glutathione level was time dependently increased significantly (P<0.05) in murine peritoneal macrophages. All the changes in peritoneal macrophages after 3 h in vitro VSSA treatment had no significant difference.

CONCLUSIONS

From this study, it may be summarized that in vitro VSSA infection not only generates excess free radical but also affects the antioxidant status and glutathione cycle in murine peritoneal macrophages.

Microbial pathogens trigger host DNA double-strand breaks whose abundance is reduced by plant defense responses

Immune responses and DNA damage repair are two fundamental processes that have been characterized extensively, but the links between them remain largely unknown. We report that multiple bacterial, fungal and oomycete plant pathogen species induce double-strand breaks (DSBs) in host plant DNA. DNA damage detected by histone γ-H2AX abundance or DNA comet assays arose hours before the disease-associated necrosis caused by virulent Pseudomonas syringae pv. tomato. Necrosis-inducing paraquat did not cause detectable DSBs at similar stages after application. Non-pathogenic E. coli and Pseudomonas fluorescens bacteria also did not induce DSBs. Elevation of reactive oxygen species (ROS) is common during plant immune responses, ROS are known DNA damaging agents, and the infection-induced host ROS burst has been implicated as a cause of host DNA damage in animal studies. However, we found that DSB formation in Arabidopsis in response to P. syringae infection still occurs in the absence of the infection-associated oxidative burst mediated by AtrbohD and AtrbohF. Plant MAMP receptor stimulation or application of defense-activating salicylic acid or jasmonic acid failed to induce a detectable level of DSBs in the absence of introduced pathogens, further suggesting that pathogen activities beyond host defense activation cause infection-induced DNA damage. The abundance of infection-induced DSBs was reduced by salicylic acid and NPR1-mediated defenses, and by certain R gene-mediated defenses. Infection-induced formation of γ-H2AX still occurred in Arabidopsis atr/atm double mutants, suggesting the presence of an alternative mediator of pathogen-induced H2AX phosphorylation. In summary, pathogenic microorganisms can induce plant DNA damage. Plant defense mechanisms help to suppress rather than promote this damage, thereby contributing to the maintenance of genome integrity in somatic tissues.

Multicellular organisms are continuously exposed to microbes and have developed sophisticated defense mechanisms to counter attack by microbial pathogens. Organisms also encounter many types of DNA damage and have evolved multiple mechanisms to maintain their genomic integrity. Even though these two fundamental responses have been characterized extensively, the relationship between them remains largely unclear. Our study demonstrates that microbial plant pathogens with diverse life styles, including bacteria, oomycete and fungal pathogens, induce double-strand breaks (DSBs) in the genomes of infected host plant cells. DSB induction is apparently a common feature during plant-pathogen interactions. DSBs are the most deleterious form of DNA damage and can lead to chromosomal aberrations and gene mutations. In response to pathogen infection, plant immune responses are activated and contribute to suppressing pathogen-induced DSBs, thereby maintaining better genome integrity and stability. The findings identify important ways that the plant immune and DNA damage repair responses are interconnected. Awareness of the above phenomena may foster future development of disease management approaches that improve crop productivity under biotic stress.

Glucose-6-phosphate dehydrogenase (G6PD)-deficient epithelial cells are less tolerant to infection by Staphylococcus aureus

Glucose-6-phosphate dehydrogenase (G6PD) is a key enzyme in the pentose phosphate pathway and provides reducing energy to all cells by maintaining redox balance. The most common clinical manifestations in patients with G6PD deficiency are neonatal jaundice and acute hemolytic anemia. The effects of microbial infection in patients with G6PD deficiency primarily relate to the hemolytic anemia caused by Plasmodium or viral infections and the subsequent medication that is required. We are interested in studying the impact of bacterial infection in G6PD-deficient cells. G6PD knock down A549 lung carcinoma cells, together with the common pathogen Staphylococcus aureus, were employed in our cell infection model. Here, we demonstrate that a lower cell viability was observed among G6PD-deficient cells when compared to scramble controls upon bacterial infection using the MTT assay. A significant increase in the intracellular ROS was detected among S. aureus-infected G6PD-deficient cells by observing dichlorofluorescein (DCF) intensity within cells under a fluorescence microscope and quantifying this signal using flow cytometry. The impairment of ROS removal is predicted to enhance apoptotic activity in G6PD-deficient cells, and this enhanced apoptosis was observed by annexin V/PI staining under a confocal fluorescence microscope and quantified by flow cytometry. A higher expression level of the intrinsic apoptotic initiator caspase-9, as well as the downstream effector caspase-3, was detected by Western blotting analysis of G6PD-deficient cells following bacterial infection. In conclusion, we propose that bacterial infection, perhaps the secreted S. aureus α-hemolysin in this case, promotes the accumulation of intracellular ROS in G6PD-deficient cells. This would trigger a stronger apoptotic activity through the intrinsic pathway thereby reducing cell viability when compared to wild type cells.

Efficacy of two novel 2,2'-bifurans to inhibit methicillin-resistant Staphylococcus aureus infection in male mice in comparison to vancomycin

The therapeutic efficacy of two novel bifurans and vancomycin in an animal model of a methicillin-resistant Staphylococcus aureus (MRSA) infection was compared. Adult male CF-1 mice (25-35 g) were intraperitoneally injected with 200 μL/mouse containing 10(7) cell-forming units of MRSA. After 16 hours, animals were treated with 110 mg/kg of vancomycin, or 5 mg/kg of mononitrile bifuran (1A) or monocationic bifuran (1B) and killed after 8 hours. Treatment with bifurans did not cause any toxicity. Treatment of MRSA-infected animals with bifurans resulted in significant reductions in the viable bacterial count in blood, liver, kidney, and spleen. Colonies recovered from livers and kidneys of mice injected with 1A or 1B lost the initial resistance pattern and became susceptible to methicillin and ciprofloxacin. MRSA elevated the serum urea level and activities of alanine aminotransferase and γ-glutamyl transpeptidase. MRSA also elevated the hepatic level of malondialdehyde, and serum levels of tumor necrosis factor and interleukin-6. MRSA also reduced the glutathione content and activities of catalase and glutathione S-transferase in liver. Similar to vancomycin, bifurans ameliorated most of the previous effects. Compound 1B was superior to 1A, and sometimes both provided better antistaphylococcal agents than vancomycin against MRSA pathogenesis. The present findings along with our previous studies support further evaluation of the efficacy of these bifurans in clinical studies.

Staphylococcus aureus Infection Induced Oxidative Imbalance in Neutrophils: Possible Protective Role of Nanoconjugated Vancomycin

Staphylococcus aureus infection causes oxidative stress in neutrophils. The immune cells use reactive oxygen species (ROS) for carrying out their normal functions while an excess amount of ROS can attack cellular components that lead to cell damage. The present study was aimed to test the protective role of nanoconjugated vancomycin against vancomycin-sensitive Staphylococcus aureus (VSSA) and vancomycin-resistant Staphylococcus aureus (VRSA) infection induced oxidative stress in neutrophils. VSSA- and VRSA-infection were developed in Swiss mice by intraperitoneal injection of 5 × 10(6) CFU/mL bacterial solutions. Nanoconjugated vancomycin was treated to VSSA- and VRSA-infected mice at its effective dose for 10 days. Vancomycin was treated to VSSA and VRSA infected mice at similar dose, respectively, for 10 days. The result reveals that in vivo VSSA and VRSA infection significantly increases the level of lipid peroxidation, protein oxidation, oxidized glutathione level, and nitrite generation and decreases the level of reduced glutathione, antioxidant enzyme status, and glutathione-dependent enzymes as compared to control group; which were increased or decreased significantly near to normal in nanoconjugated vancomycin-treated group. These finding suggests the potential use and beneficial protective role of nanoconjugated vancomycin against VSSA and VRSA infection induced oxidative imbalance in neutrophils.