Application of Antimicrobial Peptides of the Innate Immune System in Combination With Conventional Antibiotics—A Novel Way to Combat Antibiotic Resistance?

Rapidly growing resistance of pathogenic bacteria to conventional antibiotics leads to inefficiency of traditional approaches of countering infections and determines the urgent need for a search of fundamentally new anti-infective drugs. Antimicrobial peptides (AMPs) of the innate immune system are promising candidates for a role of such novel antibiotics. However, some cytotoxicity of AMPs toward host cells limits their active implementation in medicine and forces attempts to design numerous structural analogs of the peptides with optimized properties. An alternative route for the successful AMPs introduction may be their usage in combination with conventional antibiotics. Synergistic antibacterial effects have been reported for a number of such combinations, however, the molecular mechanisms of the synergy remain poorly understood and little is known whether AMPs cytotoxicy for the host cells increases upon their application with antibiotics. Our study is directed to examination of a combined action of natural AMPs with different structure and mode of action (porcine protegrin 1, caprine bactenecin ChBac3.4, human alpha- and beta-defensins (HNP-1, HNP-4, hBD-2, hBD-3), human cathelicidin LL-37), and egg white lysozyme with varied antibiotic agents (gentamicin, ofloxacin, oxacillin, rifampicin, polymyxin B, silver nanoparticles) toward selected bacteria, including drug-sensitive and drug-resistant strains, as well as toward some mammalian cells (human erythrocytes, PBMC, neutrophils, murine peritoneal macrophages and Ehrlich ascites carcinoma cells). Using “checkerboard titrations” for fractional inhibitory concentration indexes evaluation, it was found that synergy in antibacterial action mainly occurs between highly membrane-active AMPs (e.g., protegrin 1, hBD-3) and antibiotics with intracellular targets (e.g., gentamicin, rifampcin), suggesting bioavailability increase as the main model of such interaction. In some combinations modulation of dynamics of AMP-bacterial membrane interaction in presence of the antibiotic was also shown. Cytotoxic effects of the same combinations toward normal eukaryotic cells were rarely synergistic. The obtained data approve that combined application of antimicrobial peptides with antibiotics or other antimicrobials is a promising strategy for further development of new approach for combating antibiotic-resistant bacteria by usage of AMP-based therapeutics. Revealing the conventional antibiotics that increase the activity of human endogenous AMPs against particular pathogens is also important for cure strategies elaboration

Electrospun magnetic composite poly-3-hydroxybutyrate/magnetite scaffolds for biomedical applications: composition, structure, magnetic properties, and biological performance

Magnetically responsive composite polymer scaffolds have good potential for a variety of biomedical applications. In this work, electrospun composite scaffolds made of polyhydroxybutyrate (PHB) and magnetite (Fe3O4) particles (MPs) were studied before and after degradation in either PBS or a lipase solution. MPs of different sizes with high saturation magnetization were synthesized by the coprecipitation method followed by coating with citric acid (CA). Nanosized MPs were prone to magnetite-maghemite phase transformation during scaffold fabrication, as revealed by Raman spectroscopy; however, for CA-functionalized nanoparticles, the main phase was found to be magnetite, with some traces of maghemite. Submicron MPs were resistant to the magnetite-maghemite phase transformation. MPs did not significantly affect the morphology and diameter of PHB fibers. The scaffolds containing CA-coated MPs lost 0.3 or 0.2% of mass in the lipase solution and PBS, respectively, whereas scaffolds doped with unmodified MPs showed no mass changes after 1 month of incubation in either medium. In all electrospun scaffolds, no alterations of the fiber morphology were observed. Possible mechanisms of the crystalline-lamellar-structure changes in hybrid PHB/Fe3O4 scaffolds during hydrolytic and enzymatic degradation are proposed. It was revealed that particle size and particle surface functionalization affect the mechanical properties of the hybrid scaffolds. The addition of unmodified MPs increased scaffolds' ultimate strength but reduced elongation at break after the biodegradation, whereas simultaneous increases in both parameters were observed for composite scaffolds doped with CA-coated MPs. The highest saturation magnetization-higher than that published in the literature-was registered for composite PHB scaffolds doped with submicron MPs. All PHB scaffolds proved to be biocompatible, and the ones doped with nanosized MPs yielded faster proliferation of rat mesenchymal stem cells. In addition, all electrospun scaffolds were able to support angiogenesis in vivo at 30 days after implantation in Wistar rats

Human antimicrobial peptides in autoimmunity

Antimicrobial peptides (AMPs) were firstly discovered as cytotoxic substances that killed bacteria. Later they were described as biologically active peptides that are able not only to kill invaders but also to modulate host immunity. In particular, it is shown that human antimicrobial peptides are able to influence the activity of different innate and adaptive immunity components, thus, obviously, they also participate in autoimmune processes. In this review we discuss the nature of human AMPs and analyze their role in such autoimmune disorders like type 1 diabetes mellitus, rheumatoid arthritis, systemic lupus erythematosus, psoriasis, Crohn’s disease and sarcoidosis. These peptides were shown to have a “double-sided” influence on the autoimmune disease pathogenesis. Thus, described facts should be taken into account for the development of new pharmaceutical agents to cure patients with autoimmune disorders. These agents could derive from natural antimicrobial peptides that in some cases modulate immune response. For example, it was shown that human AMPs are able to modulate complement system dysregulation of which is known to be one of the most dangerous pathogenic factors during autoimmune processes

Combined Use of Antimicrobial Peptides with Antiseptics against Multidrug-Resistant Bacteria: Pros and Cons

Antimicrobial peptides (AMPs) are acknowledged as a promising template for designing new antimicrobials. At the same time, existing toxicity issues and limitations in their pharmacokinetics make topical application one of the less complicated routes to put AMPs-based therapeutics into actual medical practice. Antiseptics are one of the common components for topical treatment potent against antibiotic-resistant pathogens but often with toxicity limitations of their own. Thus, the interaction of AMPs and antiseptics is an interesting topic that is also less explored than combined action of AMPs and antibiotics. Herein, we analyzed antibacterial, antibiofilm, and cytotoxic activity of combinations of both membranolytic and non-membranolytic AMPs with a number of antiseptic agents. Fractional concentration indices were used as a measure of possible effective concentration reduction achievable due to combined application. Cases of both synergistic and antagonistic interaction with certain antiseptics and surfactants were identified, and trends in the occurrence of these types of interaction were discussed. The data may be of use for AMP-based drug development and suggest that the topic requires further attention for successfully integrating AMPs-based products in the context of complex treatment. AMP/antiseptic combinations show promise for creating topical formulations with improved activity, lowered toxicity, and, presumably, decreased chances of inducing bacterial resistance. However, careful assessment is required to avoid AMP neutralization by certain antiseptic classes in either complex drug design or AMP application alongside other therapeutics/care products

Neutrophil to Lymphocyte Ratio as a Predictor of Adverse Outcome in Patients with Decompensated Liver Cirrhosis

The natural history of liver cirrhosis (LC) is characterized by two stages: compensated and decompensated. Current clinical and laboratory prognostic models, such as Child-Pugh and MELD scales, do not take into account immune dysregulation, as well as it potential impact on the LC decompensation and the survival. Neutrophil to lymphocyte ratio (NLR) is simple and affordable parameter, representing the imbalance of two distinct immune pathways.Aim: to evaluate relationship between NLR level, mortality and SIRS development in patients with DC.Materials and methods. In this retrospective study 36 patients with DC which were hospitalized in Hepatology Department of V.H. Vasilenko clinic of propaedeutics and internal diseases, gastroenterology and hepatology, Sechenov University from January 2009 to December 2017 were enrolled. Correlation analysis, univariate and multivariable analysis were provided to find factors statistically significantly associated with lethal outcome and SIRS. The optimal cut-off levels for the NLR associated with adverse outcome were determined.Results. AIn multivariable analysis, NLR > 4 (p < 0,001) was statistically significantly associated with lethal outcome in patients with DC during hospitalization (OR: 1.57, [95 % CI 1.125–2.209], p = 0.008). Sensitivity and specificity of this cut-off is 100 % and 79.17 %, respectively. NLR > 4.8 was associated with SIRS development during hospitalization (OR: 1.484, [95 % CI 1.103–1.997], p = 0.009) with 100 % sensitivity and 90 % specificity.Conclusions. NLR is an independent risk factor of lethal outcome and SIRS development in patients with decompensated liver cirrhosis

Neutrophil to Lymphocyte Ratio as a Predictor of Adverse Outcome in Patients with Decompensated Liver Cirrhosis

The natural history of liver cirrhosis (LC) is characterized by two stages: compensated and decompensated. Current clinical and laboratory prognostic models, such as Child-Pugh and MELD scales, do not take into account immune dysregulation, as well as it potential impact on the LC decompensation and the survival. Neutrophil to lymphocyte ratio (NLR) is simple and affordable parameter, representing the imbalance of two distinct immune pathways.Aim: to evaluate relationship between NLR level, mortality and SIRS development in patients with DC.Materials and methods. In this retrospective study 36 patients with DC which were hospitalized in Hepatology Department of V.H. Vasilenko clinic of propaedeutics and internal diseases, gastroenterology and hepatology, Sechenov University from January 2009 to December 2017 were enrolled. Correlation analysis, univariate and multivariable analysis were provided to find factors statistically significantly associated with lethal outcome and SIRS. The optimal cut-off levels for the NLR associated with adverse outcome were determined.Results. AIn multivariable analysis, NLR > 4 (p < 0,001) was statistically significantly associated with lethal outcome in patients with DC during hospitalization (OR: 1.57, [95 % CI 1.125–2.209], p = 0.008). Sensitivity and specificity of this cut-off is 100 % and 79.17 %, respectively. NLR > 4.8 was associated with SIRS development during hospitalization (OR: 1.484, [95 % CI 1.103–1.997], p = 0.009) with 100 % sensitivity and 90 % specificity.Conclusions. NLR is an independent risk factor of lethal outcome and SIRS development in patients with decompensated liver cirrhosis

Influence of Silver Nanoparticles on the Growth of Ascitic and Solid Ehrlich Adenocarcinoma: Focus on Copper Metabolism

The link between copper metabolism and tumor progression motivated us to use copper chelators for suppression of tumor growth. We assume that silver nanoparticles (AgNPs) can be used for lowering bioavailable copper. Our assumption is based on the ability of Ag(I) ions released by AgNPs in biological media and interfere with Cu(I) transport. Intervention of Ag(I) into copper metabolism leads to the replacement of copper by silver in ceruloplasmin and the decrease in bioavailable copper in the bloodstream. To check this assumption, mice with ascitic or solid Ehrlich adenocarcinoma (EAC) were treated with AgNPs using different protocols. Copper status indexes (copper concentration, ceruloplasmin protein level, and oxidase activity) were monitored to assess copper metabolism. The expression of copper-related genes was determined by real-time PCR in the liver and tumors, and copper and silver levels were measured by FAAS. Intraperitoneal AgNPs treatment beginning on the day of tumor inoculation enhanced mice survival, reduced the proliferation of ascitic EAC cells, and suppressed the activity of HIF1α, TNF-α and VEGFa genes. Topical treatment by the AgNPs, which was started together with the implantation of EAC cells in the thigh, also enhanced mice survival, decreased tumor growth, and repressed genes responsible for neovascularization. The advantages of silver-induced copper deficiency over copper chelators are discussed

Fabrication and characterization of a magnetic biocomposite of magnetite nanoparticles and reduced graphene oxide for biomedical applications

Functionalization of magnetite (Fe3O4) nanoparticles with reduced graphene oxide (rGO) with the preserved magnetic properties of the former presents great potential for applying the Fe3O4/rGO biocomposite in various biomedical applications, such as magnetic resonance imaging, as a therapeutic component in initiating tumour cell death in magnetic and photon ablation therapy, and as an effective carrier for drug delivery. In this study, magnetite nanoparticles (MNPs) with a high saturation magnetization were synthesized by co-precipitation under various conditions, followed by covalent functionalization with citric acid (CA) and subsequent attachment to rGO sheets by physical adsorption. Extensive characterization revealed increasing phase purity with a subsequent decrease in the crystallite size and average size of the MNPs synthesized in an inert atmosphere compared to ambient conditions. Meanwhile, further functionalization of the MNPs with CA by covalent binding does not affect the MNP structure and size, but decreases their agglomeration. To study the magnetic properties of the MNPs and the Fe3O4/rGO composite, magnetization curves were obtained with a vibrating sample magnetometer at a pulsed magnetic field of up to 6.5 kOe. The largest values of saturation magnetization are revealed for the samples synthesized without the addition of CA in an inert atmosphere (σs = 80.27 emu/g). The addition of CA to the synthesized MNPs and Fe3O4/rGO composites reduced agglomeration, with σs values in the range from 64.10 to 60.97 emu/g. In vitro biological experiments revealed the MNP concentrations that did not cause any toxic effects on cells for use as magnetic fillers to investigate the strain-mediated effects of hybrid polymer composites on cellular behaviour due to external magnetic field exposure in the next stages of research