Dimerization and lysine substitution of melittin have differing effects on bacteria.

Introduction: Melittin is a potent antimicrobial peptide from bee venom that is effective against both Gram-positive and Gram-negative bacteria. However, it is extremely toxic to mammalian cells and, as yet, has no clinical use. Modifications to its amino acid sequence, cyclization, truncation, and dimerization have been attempted in order to reduce its toxicity whilst maintaining its antimicrobial activity.

Star-Peptide Polymers are Multi-Drug-Resistant Gram-Positive Bacteria Killers.

Antibiotic resistance in bacteria, especially Gram-positive bacteria like , is gaining considerable momentum worldwide and unless checked will pose a global health crisis. With few new antibiotics coming on the market, there is a need for novel antimicrobial materials that target and kill multi-drug-resistant (MDR) Gram-positive pathogens like methicillin-resistant (MRSA). In this study, using a novel mixed-bacteria antimicrobial assay, we show that the star-peptide polymers preferentially target and kill Gram-positive pathogens including MRSA.

The Potential of Modified and Multimeric Antimicrobial Peptide Materials as Superbug Killers.

Antimicrobial peptides (AMPs) are found in nearly all living organisms, show broad spectrum antibacterial activity, and can modulate the immune system. Furthermore, they have a very low level of resistance induction in bacteria, which makes them an ideal target for drug development and for targeting multi-drug resistant bacteria 'Superbugs'. Despite this promise, AMP therapeutic use is hampered as typically they are toxic to mammalian cells, less active under physiological conditions and are susceptible to proteolytic degradation.

Tumor Associated Macrophages: Origin, Recruitment, Phenotypic Diversity, and Targeting.

The tumor microenvironment (TME) is known to have a strong influence on tumorigenesis, with various components being involved in tumor suppression and tumor growth. A protumorigenic TME is characterized by an increased infiltration of tumor associated macrophages (TAMs), where their presence is strongly associated with tumor progression, therapy resistance, and poor survival rates. This association between the increased TAMs and poor therapeutic outcomes are stemming an increasing interest in investigating TAMs as a potential therapeutic target in cancer treatment.

A review of T helper 17 cell-related cytokines in serum and saliva in periodontitis.

Periodontitis is a chronic inflammatory disease with a complex underlying immunopathology. Cytokines, as molecular mediators of inflammation, play a role in all stages of disease progression. T helper 17 (Th17) cells are thought to play a role in periodontitis.

Peripheral memory T-cell profile is modified in patients undergoing periodontal management.

Aims: T-cells are known to have a role in periodontitis, however, the effect of periodontal therapy on peripheral memory T-cells is unclear. This study evaluated variation in peripheral memory T-cells and red complex bacteria in sub-gingival plaque in patients undergoing periodontal management.

Methods: Peripheral blood mononuclear cells and sub-gingival plaque were collected from 54 periodontitis patients at baseline, 3-, 6- and 12-months post-therapy and 40 healthy controls.

Peripheral T helper cell profiles during management of periodontitis.

Aim: Periodontitis has been associated with other systemic diseases with underlying inflammation responsible for the shared link. This study evaluated longitudinal variation in peripheral T helper cells in periodontitis patients undergoing management over 1 year.

Materials And Methods: Periodontal parameters and peripheral blood mononuclear cells (PBMCs) were collected from 54 periodontitis patients at baseline, and 3-, 6- and 12-months post-treatment and 40 healthy controls.

Peripheral neutrophil phenotypes during management of periodontitis.

Background And Objectives: Neutrophils are emerging as a key player in periodontal pathogenesis. The surface expression of cellular markers enables functional phenotyping of neutrophils which have distinct roles in disease states. This study aimed to evaluate the effect of periodontal management on neutrophil phenotypes in peripheral blood in periodontitis patients over one year.

T helper 17 cell-related cytokines in serum and saliva during management of periodontitis.

Aim: T helper (Th)17 cells are implicated in the pathogenesis of periodontitis. This study investigated the effect of periodontal management on fifteen Th17-related cytokines in serum and saliva in periodontitis patients.

Materials And Methods: Periodontal parameters, serum and saliva were collected from 40 healthy controls and 54 periodontitis subjects before treatment, and 3-, 6- and 12-months post-treatment.

Monospecies and polymicrobial biofilms differentially regulate the phenotype of genotype-specific oral cancer cells.

Microbial infection has been shown to involve in oral carcinogenesis; however, the underlying mechanisms remain poorly understood. The present study aimed to characterize the growth of oral microorganisms as both monospecies and polymicrobial biofilms and determine the effects of their products on oral keratinocytes. Candida albicans (ALC3), Actinomyces naeslundii (AN) and Streptococcus mutans (SM) biofilms or a combination of these (TRI) were grown in flow-cell system for 24 h.

Architectural Effects of Star-Shaped "Structurally Nanoengineered Antimicrobial Peptide Polymers" (SNAPPs) on Their Biological Activity.

In this work, the effect of two key structural parameters, number of arms and arm length, of star-shaped "structurally nanoengineered antimicrobial peptide polymers" (SNAPPs) on their antimicrobial activity and biocompatibility, is investigated. A library of star-shaped SNAPPs is prepared, containing varying arm numbers and arm lengths. Antimicrobial assays are then performed to assess the capacity of the SNAPPs to disrupt the membrane, inhibit the growth, and kill pathogenic bacteria.

A therapeutic gingipain vaccine induces neutralising IgG1 antibodies that protect against experimental periodontitis.

infected mice with an established -specific inflammatory immune response were protected from developing alveolar bone resorption by therapeutic vaccination with a chimera (KAS2-A1) immunogen targeting the major virulence factors of the bacterium, the gingipain proteinases. Protection was characterised by an antigen-specific IgG1 isotype antibody and Th2 cell response. Adoptive transfer of KAS2-A1-specific IgG1 or IgG2 expressing B cells confirmed that IgG1-mediated protection.

Outer Membrane Vesicles Prime and Activate Macrophage Inflammasomes and Cytokine Secretion and .

Outer membrane vesicles (OMVs) are proteoliposomes blebbed from the surface of Gram-negative bacteria. Chronic periodontitis is associated with an increase in subgingival plaque of Gram-negative bacteria, , and . In this study, we investigated the immune-modulatory effects of , and OMVs on monocytes and differentiated macrophages.

Porphyromonas gulae Activates Unprimed and Gamma Interferon-Primed Macrophages via the Pattern Recognition Receptors Toll-Like Receptor 2 (TLR2), TLR4, and NOD2.

is an anaerobic, Gram-negative coccobacillus that has been associated with periodontal disease in companion animals. The aims of this study were to analyze the ligation of pattern recognition receptors by and the subsequent activation of macrophages. Exposure of HEK cells transfected with Toll-like receptors (TLRs) or NOD-like receptors to resulted in the ligation of TLR2, TLR4, and NOD2.

Combating multidrug-resistant Gram-negative bacteria with structurally nanoengineered antimicrobial peptide polymers.

With the recent emergence of reports on resistant Gram-negative 'superbugs', infections caused by multidrug-resistant (MDR) Gram-negative bacteria have been named as one of the most urgent global health threats due to the lack of effective and biocompatible drugs. Here, we show that a class of antimicrobial agents, termed 'structurally nanoengineered antimicrobial peptide polymers' (SNAPPs) exhibit sub-μM activity against all Gram-negative bacteria tested, including ESKAPE and colistin-resistant and MDR (CMDR) pathogens, while demonstrating low toxicity. SNAPPs are highly effective in combating CMDR Acinetobacter baumannii infections in vivo, the first example of a synthetic antimicrobial polymer with CMDR Gram-negative pathogen efficacy.

Unprimed, M1 and M2 Macrophages Differentially Interact with Porphyromonas gingivalis.

Porphyromonas gingivalis is a keystone pathogen in the development of chronic periodontitis. Tissue macrophages are amongst the first immune cells to respond to bacteria and depending on the cytokine profile at the infection site, macrophages are primed to react to infection in different ways. Priming of naive macrophages with IFN-γ produces a classical pro-inflammatory, antibacterial M1 macrophage after TLR ligation, whereas priming with IL-4 induces an anti-inflammatory tissue-repair M2 phenotype.

Porphyromonas gulae Has Virulence and Immunological Characteristics Similar to Those of the Human Periodontal Pathogen Porphyromonas gingivalis.

Periodontitis is a significant problem in companion animals, and yet little is known about the disease-associated microbiota. A major virulence factor for the human periodontal pathogen Porphyromonas gingivalis is the lysyl- and arginyl-specific proteolytic activity of the gingipains. We screened several Porphyromonas species isolated from companion animals-P.

Differential Responses of Pattern Recognition Receptors to Outer Membrane Vesicles of Three Periodontal Pathogens.

Highly purified outer membrane vesicles (OMVs) of the periodontal pathogens, Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia were produced using tangential flow ultrafiltration, ultracentrifugation and Optiprep density gradient separation. Cryo-TEM and light scattering showed OMVs to be single lipid-bilayers with modal diameters of 75 to 158 nm. Enumeration of OMVs by nanoparticle flow-cytometry at the same stage of late exponential culture indicated that P.

Determination of Active Phagocytosis of Unopsonized Porphyromonas gingivalis by Macrophages and Neutrophils Using the pH-Sensitive Fluorescent Dye pHrodo.

Phagocytosis of pathogens is an important component of the innate immune system that is responsible for the removal and degradation of bacteria as well as their presentation via the major histocompatibility complexes to the adaptive immune system. The periodontal pathogen Porphyromonas gingivalis exhibits strain heterogeneity, which may affect a phagocyte's ability to recognize and phagocytose the bacterium. In addition, P.

Tannerella forsythia Outer Membrane Vesicles Are Enriched with Substrates of the Type IX Secretion System and TonB-Dependent Receptors.

Tannerella forsythia, a Gram-negative oral bacterium closely associated with chronic periodontitis, naturally produces outer membrane vesicles (OMVs). In this study, OMVs were purified by gradient centrifugation, and the proteome was investigated together with cellular fractions using LC-MS/MS analyses of SDS-PAGE fractions, resulting in the identification of 872 proteins including 297 OMV proteins. Comparison of the OMV proteome with the subcellular proteomes led to the localization of 173 proteins to the vesicle membrane and 61 proteins to the vesicle lumen, while 27 substrates of the type IX secretion system were assigned to the vesicle surface.

GM-CSF and uPA are required for Porphyromonas gingivalis-induced alveolar bone loss in a mouse periodontitis model.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and urokinase-type plasminogen activator (uPA) can contribute to the progression of chronic inflammatory diseases with possible involvement of macrophages. In this study, we investigated the role of both GM-CSF and uPA in Porphyromonas gingivalis-induced experimental periodontitis using GM-CSF-/- and uPA-/- mice. Intra-oral inoculation of wild-type (WT) C57BL/6 mice with P.

Physicochemical and immunological assessment of engineered pure protein particles with different redox states.

The development of subunit antigen delivery formulations has become an important research endeavor, especially in cases where a whole cell vaccine approach has significant biosafety issues. Particle-based systems have shown particular efficacy due to their inherent immunogenicity. In some cases, fabrication techniques can lead to changes in the redox states of encapsulated protein antigens.

Macrophage depletion abates Porphyromonas gingivalis-induced alveolar bone resorption in mice.

The role of the macrophage in the immunopathology of periodontitis has not been well defined. In this study, we show that intraoral inoculation of mice with Porphyromonas gingivalis resulted in infection, alveolar bone resorption, and a significant increase in F4/80(+) macrophages in gingival and submandibular lymph node tissues. Macrophage depletion using clodronate-liposomes resulted in a significant reduction in F4/80(+) macrophage infiltration of gingival and submandibular lymph node tissues and significantly (p < 0.

The promotion of breast cancer metastasis caused by inhibition of CSF-1R/CSF-1 signaling is blocked by targeting the G-CSF receptor.

Treatment options are limited for patients with breast cancer presenting with metastatic disease. Targeting of tumor-associated macrophages through the inhibition of colony-stimulating factor-1 receptor (CSF-1R), a key macrophage signaling pathway, has been reported to reduce tumor growth and metastasis, and these treatments are now in clinical trials. Here, we report that, surprisingly, treatment with neutralizing anti-CSF-1R and anti-CSF-1 antibodies, or with two different small-molecule inhibitors of CSF-1R, could actually increase spontaneous metastasis without altering primary tumor growth in mice bearing two independently derived mammary tumors.

Differential roles of the protein corona in the cellular uptake of nanoporous polymer particles by monocyte and macrophage cell lines.

Many biomolecules, mainly proteins, adsorb onto polymer particles to form a dynamic protein corona in biological environments. The protein corona can significantly influence particle-cell interactions, including internalization and pathway activation. In this work, we demonstrate the differential roles of a given protein corona formed in cell culture media in particle uptake by monocytes and macrophages.