Mechanism Of Killing Research Articles

Amphibian-Derived Antimicrobial Peptides: Essential Components of Innate Immunity and Potential Leads for New Antibiotic Development.

Like other vertebrates, amphibians possess innate and adaptive immune systems. At the center of the adaptive immune system is the Major Histocompatibility Complex. The important molecules of innate immunity are antimicrobial peptides (AMPs). These peptides are secreted by granular glands in the skin and protect the animal against microorganisms entering its body through the skin. AMPs offer an effective and rapid defense against pathogenic microorganisms and have cationic and amphiphilic structures. These peptides are small gene-encoded molecules of 8-50 amino acid residues synthesized by ribosomes. These small molecules typically exhibit activity against bacteria, viruses, fungi, and even cancer cells. It is known that today's amphibian AMPs originated from a common precursor gene 150 million years ago and that the origin of these peptides is preprodermaseptins. Today, antibiotic resistance has occurred due to the incorrect use of antibiotics. Traditional antibiotics are becoming increasingly inadequate. AMPs are considered promising candidates for the development of new-generation antibiotics. Therefore, new antibiotic discoveries are needed. AMPs are suitable molecules for new-generation antibiotics that are both fast and have different killing mechanisms. One of the biggest problems in the clinical applications of AMPs is their poor stability. AMPs generally have limited tropical applications because they are sensitive to protease degradation. Coating these peptides with nanomaterials to make them more stable can solve this problem.

Streamlined Access to Peptidoglycan Biosynthesis Terminator GlcNAc-1,6-anhydro-MurNAc.

GlcNAc-1,6-anhydro-MurNAc is a key peptidoglycan elongation terminator of biological and medicinal importance. Herein, we present a concise approach to this molecule in 12 steps with an overall 25% yield using d-glucosamine as the sole starting material. Our synthesis features the formation of a 1,6-anhydro-MurNAc building block by an intramolecular glycosylation and the selective conversion of the phthalimido group of the MurNPhth moiety, paving the way for antibiotics with a new killing mechanism by targeting bacterial transglycosylase.

Human γδ T cells in the tumor microenvironment: Key insights for advancing cancer immunotherapy.

The role of γδ T cells in antitumor responses has gained significant attention due to their unique major histocompatibility complex (MHC)-independent killing mechanisms, which distinguish them from conventional αβ T cells. Notably, γδ tumor-infiltrating lymphocytes (TILs) have been identified as favorable prognostic markers in various cancers. However, γδ TIL subsets, including Vδ1, Vδ2, and Vδ3, exhibit distinct prognostic implications and phenotypes from one another within the tumor microenvironment (TME). Although the underlying mechanisms remain unclear, recent studies suggest that these subset-specific differences may arise from divergent activation pathways. Vδ1 TILs appear to be mainly activated by γδ T-cell receptor (TCR) signaling, whereas Vδ2 TILs seem to rely on alternative pathways, such as natural killer (NK) receptor-mediated activation. In addition to phenotypic studies, γδ T cell-based immunotherapies are being actively developed using innovative approaches including engineered γδ T cells, γδ T cell engager molecules, and γδ TCR-based T cell therapies. Despite these advancements, challenges such as functional heterogeneity and limited in vivo persistence remain unresolved. Overcoming these obstacles could position γδ T cell therapies as a transformative platform for cancer immunotherapy. This review explores recent findings on the role of γδ T cells as prognostic markers, their phenotypic characteristics within the human TME, and recent advancements in γδ T cell-based cancer immunotherapies, offering valuable insights for the development of novel therapeutic strategies.

Photoactive broad-spectrum dressings with antimicrobial and antitumoral properties.

In this work the development of photoactive dressings (PAD) with dual purpose, is presented. These PAD can be used for the topical treatment of persistent infections caused by fungi and bacteria and are also applicable in light antitumor therapy for carcinoma. The synthesized PAD were designed employing conjugated polymer nanoparticles (CPN) doped with platinum porphyrin which serve as polymerization photoinitiators and photosensitizers for the production of reactive oxygen species (ROS). This approach led to the synthesis of N-vinyl-2-pyrrolidone (NVP) hydrogels co-polymerized with [2-(methacryloyloxy)ethyl] trimethylammonium chloride (METAC). NVP and METAC were selected to impart a good biocompatibility with eukaryotic cell lines and antimicrobial properties, respectively. The combination of METAC with an efficient photogeneration of ROS by doped CPN resulted in a material with outstanding antimicrobial features. These dressings are capable of producing an aseptic environment upon irradiation and demonstrates a bacteriostatic profile in dark conditions. Additionally, the dressings fulfill critical requirements for topical applications, providing protection and acting as a barrier, with appropriate mechanical and swelling properties; as well as adequate water vapor transmission rates. The synthesized PAD have been shown to be biocompatible and non-toxic to erythrocytes and HaCaT cell line. PAD demonstrated efficacy in eliminating microbes such as fungi and bacteria. The underlying light-induced killing mechanism involved protein photooxidation, which amplified the effects of METAC mechanism that disrupt cellular membranes. Furthermore, in vitro studies using carcinoma cell lines displayed a complete cell eradication using a relatively low light dose (36J/cm2 at 395nm). These promising results reveal also the potential of PAD in the treatment of skin cancer.

B7H6 is the predominant activating ligand driving natural killer cell-mediated killing in patients with liquid tumours: evidence from clinical, in silico, in vitro, and in vivo studies

Natural killer (NK) cells are a subset of innate lymphoid cells that are inherently capable of recognizing and killing infected or tumour cells. This has positioned NK cells as a promising live drug for tumour immunotherapy, but limited success suggests incomplete knowledge of their killing mechanism. NK cell-mediated killing involves a complex decision-making process based on integrating activating and inhibitory signals from various ligand-receptor repertoires. However, the relative importance of the different activating ligand-receptor interactions in triggering NK killing remains unclear. We employed a systematic approach combining clinical, in silico, invitro, and invivo data analysis to quantify the impact of various activating ligands. Clinical data analysis was conducted using massive pan-cancer data (n=10,595), where patients with high NK cell levels were stratified using CIBERSORT. Subsequently, multivariate Cox regression and Kaplan-Meier (KM) survival analysis were performed based on activating ligand expression. To examine the impact of ligand expression on NK killing at the cellular level, we assessed surface expression of five major activating ligands (B7H6, MICA/B, ULBP1, ULBP2/5/6, and ULBP3) of human tumour cell lines of diverse origins (n=33) via flow cytometry (FACs) and their NK cell-mediated cytotoxicity on by calcein-AM assay using human primary NK cells and NK-92cell lines. Based on this data, we quantified the contribution of each activating ligand to the NK killing activity using mathematical models and Bayesian statistics. To further validate the results, we performed calcein-AM assays upon ligand knockdown and overexpression, conjugation assays, and co-culture assays in activating ligand-downregulated/overexpressed in liquid tumour (LT) cell lines. Moreover, we established LT-xenograft mouse models to assess the efficacy of NK cell targeting toward tumours with dominant ligands. Through the clinical analysis, we discovered that among nearly all 18 activating ligands, only patients with LT who were NK cell-rich and specifically had higher B7H6 level exhibited a favorable survival outcome (p=0.0069). This unexpected dominant role of B7H6 was further confirmed by the analysis of datasets encompassing multiple ligands and a variety of tumours, which showed that B7H6 exhibited the highest contribution to NK killing among five representative ligands. Furthermore, LT cell lines (acute myeloid leukemia (AML), B cell lymphoma, and T-acute lymphocytic leukemia (ALL)) with lowered B7H6 demonstrated decreased susceptibility to NK cell-mediated cytotoxicity compared to those with higher levels. Even within the same cell line, NK cells selectively targeted cells with higher B7H6 levels. Finally, LT-xenograft mouse models (n=24) confirmed that higher B7H6 results in less tumour burden and longer survival in NK cell-treated LT mice (p=0.0022). While NK cells have gained attention for their potent anti-tumour effects without causing graft-versus-host disease (GvHD), thus making them a promising off-the-shelf therapy, our limited understanding of NK killing mechanisms has hindered their clinical application. This study illuminates the crucial role of the activating ligand B7H6 in driving NK cell killing, particularly in the context of LT. Therefore, the expression level of B7H6 could serve as a prognostic marker for patients with LT. Moreover, for the development of NK cell-based immunotherapy, focusing on increasing the level of B7H6 on its cognate receptor, NKp30, could be the most effective strategy. This work was supported by the National Research Council of Science & Technology (NST) grant (CAP-18-02-KRIBB, GTL24021-000), a National Research Foundation grant (2710012258, 2710004815), and an Institute for Basic Science grant (IBS-R029-C3).

Ajoene: a natural compound with enhanced antimycobacterial and antibiofilm properties mediated by efflux pump modulation and ROS generation against M. Smegmatis.

Tuberculosis (TB) continues to be a primary worldwide health concern due to relatively ineffective treatments. The prolonged duration of conventional antibiotic therapy warrants innovative approaches to shorten treatment courses. In response to challenges, the study explores potential of Ajoene, a naturally occurring garlic extract-derived compound, for potential TB treatment. Mycobacterium smegmatis as a model organism for M. tuberculosis (M. tb) to investigate Ajoene's efficiency. In vitro techniques like antimicrobial susceptibility, antibiofilm, EtBr accumulation assay, and ROS assay evaluate the potency of Ajoene and conventional TB drugs against Mycobacterium smegmatis. An in-silico study also investigated the interaction between Ajoene and quorum-sensing proteins, specifically regX3, MSMEG_5244, and MSMEG_3944, which are involved in biofilm formation and sliding activity. In vitro findings revealed that Ajoene exhibited significant antibacterial activity by inhibiting growth and showing bactericidal effects. It also demonstrated additive interactions with common antibiotics such as Isoniazid and Rifampicin. Furthermore, Ajoene demonstrated a comparative interaction with commonly used antibiotics, such as Isoniazid and Rifampicin, and reduced M. smegmatis motility, both alone and in combination with these antibiotics. In silico analysis shows that Ajoene exhibited a higher binding affinity with regX3, a protein orthologous to the regX3 gene in M.tb. Ajoene also demonstrated consistent antibiofilm effects, particularly when combined synergistically with Isoniazid and Rifampicin. Mechanistic investigations demonstrated Ajoene's potential to inhibit efflux pumps and promote ROS generation in bacteria, suggesting a potential direct killing mechanism. Collectively, the findings emphasize Ajoene's effectiveness as a novel antimycobacterial and antibiofilm molecule for TB treatment.

A meiotic driver hijacks an epigenetic reader to disrupt mitosis in noncarrier offspring

Killer meiotic drivers (KMDs) are selfish genetic elements that distort Mendelian inheritance by selectively killing meiotic products lacking the KMD element, thereby promoting their own propagation. Although KMDs have been found in diverse eukaryotes, only a limited number of them have been characterized at the molecular level, and their killing mechanisms remain largely unknown. In this study, we identify that a gene previously deemed essential for cell survival in the fission yeast Schizosaccharomyces pombe is a single-gene KMD. This gene, tdk1, kills nearly all tdk1Δ progeny in a tdk1+ × tdk1Δ cross. By analyzing polymorphisms of tdk1 among natural strains, we identify a resistant haplotype, HT3. This haplotype lacks killing ability yet confers resistance to killing by the wild-type tdk1. Proximity labeling experiments reveal an interaction between Tdk1, the protein product of tdk1, and the epigenetic reader Bdf1. Interestingly, the nonkilling Tdk1-HT3 variant does not interact with Bdf1. Cryoelectron microscopy further elucidated the binding interface between Tdk1 and Bdf1, pinpointing mutations within Tdk1-HT3 that disrupt this interface. During sexual reproduction, Tdk1 forms stable Bdf1-binding nuclear foci in all spores after meiosis. These foci persist in germinated tdk1Δ progeny and impede chromosome segregation during mitosis by generating aberrant chromosomal adhesions. This study identifies a KMD that masquerades as an essential gene and reveals the molecular mechanism by which this KMD hijacks cellular machinery to execute killing. Additionally, we unveil that losing the hijacking ability is an evolutionary path for this single-gene KMD to evolve into a nonkilling resistant haplotype.

Deciphering the inhibitory mechanism of antimicrobial peptide pexiganan conjugated with sodium-alginate chitosan-cholesterol nanoparticle against the opportunistic pathogen Acinetobacter baumannii

The emergence of antibiotic resistance is one of the most challenging problems of modern times as the armory of conventional antibiotics is quickly exhausting due to the rapid rise of resistance in pathogenic microorganisms. Acinetobacter baumannii, a potential member of ESKAPE group of bacteria, has a great deal of clinical importance causing severe nosocomial infections which often become life-threatening. According to the World Health Organization (WHO), antimicrobial resistance accounts for 2–3 million deaths every year across the world. Since the pathogen has the remarkable ability to acquire or upregulate various resistant determinants in the form of secreting of β-lactamase, aminoglycoside modifying enzymes, uplifting the function of efflux pumps or altering the target sites of different antibiotics; conventional antibiotic therapy often falls short to eradicate the infection. As a possible solution, the application of alternative therapy is therefore the need of the hour. Here we emphasize potentiating the antimicrobial efficacy of pexiganan, a well-known antimicrobial peptide against Gram-negative bacteria. Conjugation with nanoparticles composed of sodium-alginate and chitosan-cholesterol has increased the antimicrobial effect of the peptide on this opportunist pathogen. The evaluation of the bactericidal analysis and minimum inhibitory concentration indicates this nanocomposite can kill the bacteria at a very low concentration (3 μg/ml). When applied to the bacterial biofilm, the key factor for producing recalcitrant infection; our synthesized complex could effectively reduce the biomass in a dose-dependent manner. Later we enfold the mechanism of killing by measuring oxidative stress, cell membrane perforation by biochemical analysis. Our analysis indicates this unique nanocomposite can bypass the need of antibiotic treatment by its pore-forming ability on bacterial membrane. The nominal in-vivo toxicity and non-specific mode of action make it an interesting candidate for future therapeutics.

Deciphering the killing mechanisms of potassium iodide in combination with antimicrobial photodynamic therapy against cross-kingdom biofilm.

The co-existence of S. mutans and C. albicans is frequently detected in root caries and early child caries and is reported to be associated with recurrent caries. The aim of this study was to investigate the effects of potassium iodide (KI) in combination with toluidine blue O-mediated antimicrobial photodynamic therapy (aPDT) on S. mutans and C. albicans mixed-species biofilm, as well as the antibiofilm mechanisms involved. Mixed-species biofilm was constructed of S. mutans and C. albicans on dentin blocks. The antibiofilm efficacy, cytotoxicity and antibiofilm mechanism of KI in combination with aPDT were determined and evaluated. KI+TBO-aPDT treatment caused reduction in microorganism counts, metabolic activity, and biofilm biomass of mixed-species biofilm without inducing cytotoxicity to hDPCs (human dental pulp cells). Observations such increased ROS (reactive oxygen species) levels, impaired cell membrane function, cell apoptosis and reduced expression in several genes seem to be artifacts of reduced growth and general killing by KI+TBO-aPDT treatment. These data suggested that KI in combination with aPDT as an innovative approach to combat S. mutans and C. albicans biofilm, and thus as an optional treatment for caries.

Potential Involvement of Reactive Oxygen Species in the Bactericidal Activity of Eugenol against Salmonella Typhimurium.

There is an increasing need to develop alternative antimicrobials to replace currently used antibiotics. Phytochemicals, such as essential oils, have garnered significant attention in recent years as potential antimicrobials. However, the mechanisms underlying their bactericidal activities are not yet fully understood. In this study, we investigated the bactericidal activity of eugenol oil against Salmonella enterica serovar Typhimurium (S. Typhimurium) to elucidate its mechanism of action. We hypothesized that eugenol exerts its bactericidal effects through the production of reactive oxygen species (ROS), which ultimately leads to cell death. The result of this study demonstrated that the bactericidal activity of eugenol against S. Typhimurium was significantly (p < 0.05) mitigated by thiourea (ROS scavenger) or iron chelator 2,2'-dipyridyl, supporting the hypothesis. This finding contributes to a better understanding of the killing mechanism by eugenol oil.

Comparative Properties of Helical and Linear Amphipathicity of Peptides Composed of Arginine, Tryptophan, and Valine.

The persistence of antibiotic resistance has incited a strong interest in the discovery of agents with novel antimicrobial mechanisms. The direct killing of multidrug-resistant bacteria by cationic antimicrobial peptides (AMPs) underscores their importance in the fight against infections associated with antibiotic resistance. Despite a vast body of AMP literature demonstrating a plurality in structural classes, AMP engineering has been largely skewed toward peptides with idealized amphipathic helices (H-amphipathic). In contrast to helical amphipathicity, we designed a series of peptides that display the amphipathic motifs in the primary structure. We previously developed a rational framework for designing AMP libraries of H-amphipathic peptides consisting of Arg, Trp, and Val (H-RWV, with a confirmed helicity up to 88% in the presence of membrane lipids) tested against the most common MDR organisms. In this study, we re-engineered one of the series of the H-RWV peptides (8, 10, 12, 14, and 16 residues in length) to display the amphipathicity in the primary structure by side-by-side (linear) alignment of the cationic and hydrophobic residues into the 2 separate linear amphipathic (L-amphipathic) motifs. We compared the 2 series of peptides for antibacterial activity, red blood cell (RBC) lysis, killing and membrane-perturbation properties. The L-RWV peptides achieved the highest antibacterial activity at a minimum length of 12 residues (L-RWV12, minimum optimal length or MOL) with the lowest mean MIC of 3-4 µM, whereas the MOL for the H-RWV series was reached at 16 residues (H-RWV16). Overall, H-RWV16 displayed the lowest mean MIC at 2 µM but higher levels of RBC lysis (25-30%), while the L-RWV series displayed minor RBC lytic effects at the test concentrations. Interestingly, when the S. aureus strain SA719 was chosen because of its susceptibility to most of the peptides, none of the L-RWV peptides demonstrated a high level of membrane perturbation determined by propidium iodide incorporation measured by flow cytometry, with <50% PI incorporation for the L-RWV peptides. By contrast, most H-RWV peptides displayed almost up to 100% PI incorporation. The results suggest that membrane perturbation is not the primary killing mechanism of the L-amphipathic RWV peptides, in contrast to the H-RWV peptides. Taken together, the data indicate that both types of amphipathicity may provide different ideal pharmacological properties that deserve further investigation.

An integrated metabolomics and proteomics analysis reveals copper‑zinc alloy surface contact-mediated metabolic disruption, lipid peroxidation, and osmotic imbalance of Cryptocaryon irritans tomonts

Cryptocaryon irritans cause massive losses in the mariculture industry and are among the most threatening pathogens affecting teleost species. Copper‑zinc alloy (CZA) surface contact effectively kills C. irritans within minutes. Thus, this study employed integrated metabolomics and proteomics analysis to investigate the killing mechanism of CZA against C. irritans. Moreover, malondialdehyde contents, CuZn-SOD, and ATPase activities were evaluated. Proteomics analysis identified 142 differentially expressed proteins (DEPs), including 91 (59 upregulated, 32 downregulated), 92 (42 upregulated, 50 downregulated), and 43 (17 upregulated, 26 downregulated) DEPs at 0.5 h, 1 h, and 0.5 h vs 1 h of contact treatment with the CZA surface, respectively. Similarly, the metabolomic analysis identified 377 differentially expressed metabolites (DEMs). There were 237 (94 upregulated, 143 downregulated), 264 (112 upregulated, 152 downregulated), and 193 (101 upregulated, 92 downregulated) DEMs at 0.5 h, 1 h, and 0.5 h vs 1 h of contact treatment with the CZA surface, respectively. KEGG-based integrative analyses revealed that CZA exposure significantly enriched proteins and metabolites involved in oxidative phosphorylation, purine, pyrimidine, cysteine, and methionine metabolism. Notably, CZA exposure inhibited the TCA cycle, disrupting energy metabolism, as evidenced by downregulation of key TCA proteins, including citrate synthase and malate dehydrogenase, and metabolites like succinic and malic acids at both 0.5 h and 1 h of CZA treatment. Prolonged CZA exposure also affected protein metabolism, with significant downregulation of ribosomal protein S3a (RPS3a) and proteasome activity. Additionally, CZA surface contact downregulated key proteins involved in pyrimidine (DHFR-TS), purine (RRM1), and cysteine and methionine metabolism (AHCY), leading to disturbances in the methionine cycle, suppression of glutathione metabolism, and alterations in cellular redox status. Quantitative polymerase chain reaction (qPCR) analysis confirmed the upregulation of citrate synthase, proteasome subunit alpha type, and adenosylhomocysteinase with prolonged CZA exposure. Additionally, extended CZA exposure significantly decreased the MDA content due to the increased CuZn-SOD activity. Moreover, CZA exposure reduced Ca2+/Mg2+-ATPase and Na+/K+-ATPase activities. Altogether, CZA surface contact caused metabolic disruption, lipid peroxidation, and osmotic imbalance of C. irritans tomonts, highlighting the broad molecular impact of CZA on cellular processes.

Damping excessive viral-induced IFN-γ rescues the impaired anti-Aspergillus host immune response in influenza-associated pulmonary aspergillosis

Influenza-associated pulmonary aspergillosis (IAPA) is a severe fungal superinfection in critically ill influenza patients that is of incompletely understood pathogenesis. Despite the use of contemporary therapies with antifungal and antivirals, mortality rates remain unacceptably high. We aimed to unravel the IAPA immunopathogenesis as a means to develop adjunctive immunomodulatory therapies. We used a murine model of IAPA to investigate how influenza predisposes to the development of invasive pulmonary aspergillosis. Immunocompetent mice were challenged with an intranasal instillation of influenza on day 0 followed by an orotracheal inoculation with Aspergillus 4 days later. Mice were monitored daily for overall health status, lung pathology with micro-computed tomography (μCT) and fungal burden with bioluminescence imaging (BLI). At endpoint, high parameter immunophenotyping, spatial transcriptomics, histopathology, dynamic phagosome biogenesis assays with live imaging, immunofluorescence staining, specialized functional phagocytosis and killing assays were performed. We uncovered an early exuberant influenza-induced interferon-gamma (IFN-γ) production as the major driver of immunopathology in IAPA and delineated the molecular mechanisms. Specifically, excessive IFN-γ production resulted in a defective Th17-immune response, depletion of macrophages, and impaired killing of Aspergillus conidia by macrophages due to the inhibition of NADPH oxidase-dependent activation of LC3-associated phagocytosis (LAP). Markedly, mice with partial or complete genetic ablation of IFN-γ had a restored Th17-immune response, LAP-dependent mechanism of killing and were fully protected from invasive fungal infection. Together, these results identify exuberant viral induced IFN-γ production as a major driver of immune dysfunction in IAPA, paving the way to explore the use of excessive viral-induced IFN-γ as a biomarker and new immunotherapeutic target in IAPA. This research was funded by the Research Foundation Flanders (FWO), project funding under Grant G053121N to JW, SHB and GVV; G057721N, G0G4820N to GVV; 1506114N to KL and GVV; KU Leuven internal funds (C24/17/061) to GVV, clinical research funding to JW, Research Foundation Flanders (FWO) aspirant mandate under Grant 1186121N/1186123N to LS, 11B5520N to FS, 1SF2222N to EV and 11M6922N/11M6924N to SF, travel grants V428023N, K103723N, K217722N to LS. FLvdV was supported by a Vidi grant of the Netherlands Association for Scientific Research. FLvdV, JW, AC and GC were supported by the Europeans Union's Horizon 2020 research and innovation program under grant agreement no 847507 HDM-FUN. AC was also supported by the Fundação para a Ciência e a Tecnologia (FCT), with the references UIDB/50026/2020, UIDP/50026/2020, PTDC/MED-OUT/1112/2021 (https://doi.org/10.54499/PTDC/MED-OUT/1112/2021), and 2022.06674.PTDC (http://doi.org/10.54499/2022.06674.PTDC); and the "la Caixa" Foundation under the agreement LCF/PR/HR22/52420003 (MICROFUN).

A multifunctional hydrogel dressing loaded with antibiotics for healing of infected wound

Wound bacterial infections can significantly delay the healing process and even lead to fetal sepsis. There is a need for multifunctional dressings that possess antibacterial property, tissue adhesive property, self-healing capability, and biocompatibility to effectively treat bacteria-infected wound. In this study, we report a dual dynamically crosslinked hydrogel, OHA-PBA/PVA/Gen, which incorporates the antibiotic gentamicin (Gen) as a dynamic crosslinker. The hydrogel is formed through the formation of Schiff base bonds between phenylboronic acid-grafted oxidized hyaluronic acid (OHA-PBA) and Gen, as well as boronic acid ester bonds between OHA-PBA and polyvinyl alcohol (PVA). This unique composition imparts tissue adhesiveness, injectability and self-healing property to the hydrogel. The hydrogel also exhibits pH-responsive antibiotic release behavior due to the acid-responsive dissociation of Schiff base bonds. As a result, it demonstrates strong antibacterial activity against both Gram-positive bacteria S. aureus and Gram-negative bacteria E. coli through contact killing and diffusion killing mechanisms. Importantly, the OHA-PBA/PVA/Gen hydrogel avoids incorporation of toxic small molecular crosslinking agents, and all the components of the hydrogel are biocompatible, ensuring its biosafety. In a S. aureus-infected wound mouse model, this hydrogel effectively eradicated bacteria and promoted angiogenesis, leading to significantly accelerated wound healing. These results highlight the potential of the dual dynamically crosslinking hydrogel OHA-PBA/PVA/Gen as a multifunctional wound dressing for the treatment of bacteria-infected wound.

Vaping and Orthopedic Surgery: Perioperative Management

The growing use of electronic cigarettes (ECs) as a perceived safer alternative to traditional combustible smoking has significant implications for orthopedic surgery patients. Surgeons need to recognize the harms and risks associated with ECs beyond their nicotine content. EC aerosols contain cytotoxic elements, including harmful chemicals, carcinogens, heavy metals, and flavoring agents. They can induce oxidative stress, resulting from an imbalance between cell antioxidant defense and reactive oxygen species (ROS). These effects can compromise bone repair, particularly with skeletal system disorders. Furthermore, ECs’ impact on wound healing and surgical site infection (SSI) have been well-documented. Smoking can reduce the inflammatory healing response, impair oxidative bacterial killing mechanisms, delay the proliferation healing response, and alter collagen metabolism. Some surgical practices remain unchanged despite physicians’ efforts to inquire about EC use. Most orthopedic surgeons do not delay surgery due to nicotine consumption, and urine tests for nicotine are rarely used. However, preoperative smoking cessation interventions offer a unique opportunity to help patients stop consuming nicotine. Therefore, it is crucial for orthopedic surgeons to understand the harms of ECs and communicate the associated risks to patients.

Enhancement of gold-curcumin nanoparticle mediated radiation response for improved therapy in cervical cancer: a computational approach and predictive pathway analysis.

Radiotherapy is prevalently applied for highly effective cancer therapy while the low specificity of radiation is deleterious to the nearby healthy cells. High-Z-based nanomaterials offer excellent radio-enhancement properties while natural products provide radioprotection. Modulation of the radiotherapeutic index via applying nanomaterials is feasible for effective treatment however, the scenario changes when simultaneous protection of non-cancerous cells is required. Here, we report the modulatory radiotherapeutic effect of curcumin conjugated gold nanoparticles in a single nanoformulation to pave the long-awaited hope of a single combination-based, cell-selective radio enhancer, and protectant for cancer radiotherapy. We have validated the effective radiation dose along with the combination of the radio-nano-modulator by a reverse experimentation statistical model. The concept was supported by different sets of experiments, like quantification of ROS generation, cell cycle monitoring, mitochondrial membrane potential measurement, etc. along with gene expression study, and predictive modeling of molecular pathways of the killing mechanism. In conclusion, the nanoconjugate showed a promise to become a candidate for the pH-dependent cell-specific radio-modulator.

Impact of Conjugation of the Reactive Oxygen Species (ROS)-Generating Catalytic Moiety with Membrane-Active Antimicrobial Peptoids: Promoting Multitarget Mechanism and Enhancing Selectivity.

Antimicrobial peptides (AMPs) represent promising therapeutic modalities against multidrug-resistant bacterial infections. As a mimic of natural AMPs, peptidomimetic oligomers like peptoids (i.e., oligo-N-substituted glycines) have been utilized for antimicrobials with resistance against proteolytic degradation. Here, we explore the conjugation of catalytic metal-binding motifs─the amino terminal Cu(II) and Ni(II) binding (ATCUN) motif─with cationic amphipathic antimicrobial peptoids to enhance their efficacy. Upon complexation with Cu(II) or Ni(II), the conjugates catalyzed hydroxyl radical generation, and 22 and 22-Cu exhibited over 10-fold improved selectivity compared to the parent peptoid, likely due to reduced hydrophobicity. Cu-ATCUN-peptoids caused bacterial membrane disruption, aggregation of intracellular biomolecules, DNA oxidation, and lipid peroxidation, promoting multiple killing mechanisms. In a mouse sepsis model, 22 demonstrated antimicrobial and anti-inflammatory efficacy with low toxicity. This study suggests a strategy to improve the potency of membrane-acting antimicrobial peptoids by incorporating ROS-generating motifs, thereby adding oxidative damage as a killing mechanism.

IRF2 loss is associated with reduced MHC I pathway transcripts in subsets of most human cancers and causes resistance to checkpoint immunotherapy in human and mouse melanomas.

In order for cancers to progress, they must evade elimination by CD8 T cells or other immune mechanisms. CD8 T cells recognize and kill tumor cells that display immunogenic tumor peptides bound to MHC I molecules. One of the ways that cancers can escape such killing is by reducing expression of MHC I molecules, and loss of MHC I is frequently observed in tumors. There are multiple different mechanisms that can underly the loss of MHC I complexes on tumor and it is currently unclear whether there are particular mechanisms that occur frequently and, if so, in what types of cancers. Also of importance to know is whether the loss of MHC I is reversible and how such loss and/or its restoration would impact responses to immunotherapy. Here, we investigate these issues for loss of IRF1 and IRF2, which are transcription factors that drive expression of MHC I pathway genes and some killing mechanisms. Bioinformatics analyses of IRF2 and IRF2-dependent gene transcripts were performed for all human cancers in the TCGA RNAseq database. IRF2 protein-DNA-binding was analyzed in ChIPseq databases. CRISRPcas9 was used to knock out IRF1 and IRF2 genes in human and mouse melanoma cells and the resulting phenotypes were analyzed in vitro and in vivo. Transcriptomic analysis revealed that IRF2 expression was reduced in a substantial subset of cases in almost all types of human cancers. When this occurred there was a corresponding reduction in the expression of IRF2-regulated genes that were needed for CD8 T cell recognition. To test cause and effect for these IRF2 correlations and the consequences of IRF2 loss, we gene-edited IRF2 in a patient-derived melanoma and a mouse melanoma. The IRF2 gene-edited melanomas had reduced expression of transcripts for genes in the MHC I pathway and decreased levels of MHC I complexes on the cell surface. Levels of Caspase 7, an IRF2 target gene involved in CD8 T cell killing of tumors, were also reduced. This loss of IRF2 caused both human and mouse melanomas to become resistant to immunotherapy with a checkpoint inhibitor. Importantly, these effects were reversible. Stimulation of the IRF2-deficient melanomas with interferon induced the expression of a functionally homologous transcription factor, IRF1, which then restored the MHC I pathway and responsiveness to CPI. Our study shows that a subset of cases within most types of cancers downregulates IRF2 and that this can allow cancers to escape immune control. This can cause resistance to checkpoint blockade immunotherapy and is reversible with currently available biologics.

Agent-Based Modeling of Virtual Tumors Reveals the Critical Influence of Microenvironmental Complexity on Immunotherapy Efficacy.

Since the introduction of the first immune checkpoint inhibitor (ICI), immunotherapy has changed the landscape of molecular therapeutics for cancers. However, ICIs do not work equally well on all cancers and for all patients. There has been a growing interest in using mathematical and computational models to optimize clinical responses. Ordinary differential equations (ODEs) have been widely used for mechanistic modeling in immuno-oncology and immunotherapy. They allow rapid simulations of temporal changes in the cellular and molecular populations involved. Nonetheless, ODEs cannot describe the spatial structure in the tumor microenvironment or quantify the influence of spatially-dependent characteristics of tumor-immune dynamics. For these reasons, agent-based models (ABMs) have gained popularity because they can model more detailed phenotypic and spatial heterogeneity that better reflect the complexity seen in vivo. In the context of anti-PD-1 ICIs, we compare treatment outcomes simulated from an ODE model and an ABM to show the importance of including spatial components in computational models of cancer immunotherapy. We consider tumor cells of high and low antigenicity and two distinct cytotoxic T lymphocyte (CTL) killing mechanisms. The preferred mechanism differs based on the antigenicity of tumor cells. Our ABM reveals varied phenotypic shifts within the tumor and spatial organization of tumor and CTLs despite similarities in key immune parameters, initial simulation conditions, and early temporal trajectories of the cell populations.

CycP: A Novel Self-Assembled Vesicle-Forming Cyclic Antimicrobial Peptide to Control Drug-Resistant S. aureus.

Antimicrobial peptides (AMPs) are considered a promising alternative to conventional antibiotics to fight against the rapid evolution of antibiotic resistance. Other than their potent antimicrobial properties, AMP-based vesicles can be used as efficient drug-delivery vehicles. In the present study, we synthesized and characterized a new cyclic AMP, consisting of all-hydrophobic cores with antimicrobial activity against S. aureus. Interestingly, CycP undergoes supramolecular self-assembly, and self-assembled CycP (sCycP) vesicles are characterized under an electron microscope; however, these vesicles do not display antimicrobial activity. Next, sCycP vesicles are used in combination with SXT (sulfamethoxazole-trimethoprim) vesicles to check the drug loading and delivery capacity of sCycP vesicles to bacterial cell membranes. Interestingly, sCycP vesicles showed synergistic action with SXT vesicles and resulted in a significant reduction in MIC against S. aureus. Further, electron microscopy confirmed the membrane-specific killing mechanism of SXT-loaded sCycP vesicles. Additionally, CycP showed high binding affinities with the β-lactamase of S. aureus, which was one of its possible antimicrobial mechanisms of action. Overall, the results suggested that CycP is a novel self-assembled dual-action cyclic AMP with non-cytotoxic properties that can be used alone as an AMP or a self-assembled drug delivery vehicle for antibiotics to combat S. aureus infections.