Peptide LL-37 Research Articles

The PdxR-PdxKU locus involved in vitamin B6 salvage is important for group A streptococcal resistance to neutrophil killing and survival in human blood.

Streptococcus pyogenes (Group A Streptococcus, GAS) is a Gram-positive bacterium that inflicts both superficial and life-threatening diseases on its human host. Analysis of fitness using a transposon mutant library revealed that genes predicted to be involved in vitamin B6 acquisition are associated with fitness in whole human blood. Vitamin B6 is essential for all life and is important for many cellular functions. In several streptococcal species, it has been shown that mutants in B6 acquisition exhibited reduced virulence phenotypes and were attenuated during infection. In GAS, B6 acquisition is believed to be controlled by the pdxR-pdxKU locus, where PdxR is a positive regulator of pdxKU, which encodes for a B6-substrate kinase and permease, respectively. Mutants in the regulator (ΔpdxR) and salvage machinery (ΔpdxKU) both exhibited modest growth defects when grown in oxygenated conditions with limited vitamin B6 precursors. ∆pdxR and ∆pdxKU mutants also exhibited an impaired ability to survive when challenged with whole human or mouse blood. This defect was characterized by reduced survival in the presence of human neutrophil-like HL60s, primary polymorphonuclear leukocytes, and antimicrobial peptide LL-37. Promoter analysis showed that PdxR is an autoregulator and activated pdxKU in the absence of B6. Interestingly, ∆pdxR and ∆pdxKU mutants were not attenuated in mouse models of infection, suggesting a species-specific impact on virulence. Overall, it appears that pdxR-pdxKU is associated with GAS vitamin B6 metabolism as well as pathogen survival during encounters with the human innate immune system.IMPORTANCEBacterial pathogens such as Streptococcus pyogenes (Group A Streptococcus, GAS) must be able to obtain needed nutrients in their human host. Vitamin B6 or pyridoxal 5' phosphate is essential for all life and is important for many cellular functions. In other streptococcal pathogens, B6 acquisition has been shown to be important for their ability to cause disease. Here, we show that loss of the putative vitamin B6 salvage pathway locus pdxR-pdxKU affects GAS pathogenesis when encountering innate immune responses from phagocytic neutrophils and antimicrobial peptides within the host. pdxR-pdxKU may contribute to oxygen tolerance through B6; however, there appear to be other mechanisms for salvaging vitamin B6. Overall, pdxR-pdxKU is associated with GAS resistance to the human innate immune response and oxygen tolerance and contributes modestly to B6 metabolism.

Tissue nano-transfection of antimicrobial genes drives bacterial biofilm killing in wounds and is potentially mediated by extracellular vesicles

The emergence of bacteria that are resistant to antibiotics is on track to become a major global health crisis. Therefore, there is an urgent need for new treatment options. Here, we studied the implementation of tissue-nanotransfection (TNT) to treat Staphylococcus aureus-infected wounds by delivering gene cargos that boost the levels of naturally produced antimicrobial peptides. The Cathelicidin Antimicrobial Peptide gene (CAMP), which produces the antimicrobial peptide LL-37, was used as model gene cargo. In vitro evaluation showed successful transfection and an increase in the transcription and translation of CAMP-coding plasmid in mouse primary epithelial cells. Moreover, we found that the extracellular vesicles (EVs) derived from the transfected cells (in vitro and in vivo) carried significantly higher concentrations of CAMP transcripts and LL-37 peptide compared to control EVs, possibly mediating the trafficking of the antimicrobial contents to other neighboring cells. The TNT platform was then used in vivo on an excisional wound model in mice to nanotransfect the CAMP-coding plasmid on the edge of infected wounds. After 4 days of daily treatment, we observed a significant decrease in the bacterial load in the CAMP-treated group compared to the sham group. Moreover, histological analysis and bacterial load quantification also revealed that TNT of CAMP on S. aureus-infected wounds was effective in treating biofilm progression by reducing the bacterial load. Lastly, we observed a significant increase in macrophage recruitment to the infected tissue, a robust increase in vascularization, as well as and an increased expression of IL10 and Fli1. Our results demonstrate that TNT-based delivery of gene cargos coding for antimicrobial compounds to the wound is a promising approach for combating biofilm infections in wounds.

Photocatalytic Degradation of Bacterial Lipopolysaccharides by Peptide-Coated TiO2 Nanoparticles.

In this study, we report the degradation of smooth and rough lipopolysaccharides (LPS) from Gram-negative bacteria and of lipoteichoic acid (LTA) from Gram-positive bacteria by peptide-coated TiO2 nanoparticles (TiO2 NPs). While bare TiO2 NPs displayed minor binding to both LPS and LTA, coating TiO2 NPs with the antimicrobial peptide LL-37 dramatically increased the level of binding to both LPS and LTA, decorating these uniformly. Importantly, peptide coating did not suppress reactive oxygen species generation of TiO2 NPs; hence, UV illumination triggered pronounced degradation of LPS and LTA by peptide-coated TiO2 NPs. Structural consequences of oxidative degradation were examined by neutron reflectometry for smooth LPS, showing that degradation occurred preferentially in its outer O-antigen tails. Furthermore, cryo-TEM and light scattering showed lipopolysaccharide fragments resulting from degradation to be captured by the NP/lipopolysaccharide coaggregates. The capacity of LL-37-TiO2 NPs to capture and degrade LPS and LTA was demonstrated to be of importance for their ability to suppress lipopolysaccharide-induced activation in human monocytes at simultaneously low toxicity. Together, these results suggest that peptide-coated photocatalytic NPs offer opportunities for the confinement of infection and inflammation.

Colloidal Structure Dictates Antimicrobial Efficacy in LL-37 Self-Assemblies With Glycerol Monooleate.

The antimicrobial peptide LL-37 is a promising alternative to conventional antibiotics to combat bacteria in suspension and biofilms. Its self-assembly with polar lipids is suggested to improve its potential for therapeutic applications with higher stability against degradation and bioavailability. This study investigates the self-assembly of LL-37 with glyceryl monooleate (GMO), establishing the link between colloidal structure and antimicrobial activity. Small-angle X-ray scattering, dynamic light scattering and cryogenic transmission electron microscopy show structural transformation from dispersions of inverse bicontinuous structure (cubosomes) to multilamellar vesicles and direct rod-like mixed-micelles upon increasing the content of LL-37 in GMO. In vitro assays against planktonic and biofilm cells demonstrate that 128 µg mL-1 of GMO cubosomes have no impact on Pseudomonas aeruginosa. Still, the cubosomes reduce the Staphylococcus aureus planktonic population by ≈ 1-log after 24 h. Cylindrical micelles formed at LL-37/GMO 9/1 and 8/2 with 128 µg mL-1 LL-37 decrease the Pseudomonas aeruginosa population by 6-log. This activity is gradually abolished when LL-37 is encapsulated in vesicles or cubosomes. They also demonstrate low antibiofilm efficacy and promote the biomass of Staphylococcus aureus biofilms. These results highlight the importance of colloidal structure for therapeutic outcomes, providing insights for advanced lipid nanocarrier designs.

Hypoxic culture enhances the antimicrobial activity of amnion-derived mesenchymal stem cells, thereby reducing bacterial load and promoting wound healing in diabetic mice

BackgroundConditioned medium from amnion-derived mesenchymal stem cells (AMSCs) enhances wound healing, a process that is further improved under hypoxic culture conditions. Diabetic foot ulcers are difficult to treat and are frequently complicated by a high rate of bacterial infections, mainly Staphylococcus aureus, which can lead to limb amputation and death. Here, we topically applied conditioned medium from AMSCs cultured under hypoxic conditions to S. aureus-infected wounds in diabetic mice to investigate its effect on bacterial counts and wound healing. MethodsWe prepared conditioned medium by culturing AMSCs under 21% or 1% O2 and investigated its effects on S. aureus. We infected skin wounds of diabetic mice with S. aureus and treated these with hydrogels containing the conditioned medium to examine its effect on bacterial inhibition and wound healing. ResultsConditioned medium from AMSCs cultured under 1% O2 contained higher levels of the antimicrobial peptide LL-37. It significantly inhibited S. aureus growth in vitro, reduced bacterial counts in infected wounds, and facilitated wound closure in diabetic mice. ConclusionsHydrogels containing conditioned medium from hypoxically cultured AMSCs inhibited the growth of S. aureus and promoted wound healing in a mouse model of diabetic wounds.

Antibacterial periodontal ligament stem cells enhance periodontal regeneration and regulate the oral microbiome

BackgroundThe transplantation of periodontal ligament stem cells (PDLSCs) has been shown to enhance periodontal regeneration in animal models and clinical trials. However, it is not known whether PDLSCs are antibacterial and whether this affects oral microbiota and periodontal regeneration.MethodsWe isolated human PDLSCs from periodontal ligament of extracted teeth. Rats’ periodontal fenestration defects were prepared, and treated with PDLSC injections (Cell group), using saline injections (Saline group) as the control. The oral microbiota was explored by 16 S rDNA sequencing and compared with that before surgery (PRE group). The antibacterial property of PDLSCs and its underlying mechanism were tested in vitro.ResultsMicrobiome analyses reveal a decreased biodiversity, a changed community structure, and downregulated community functions of the oral microbiome in the Saline group. PDLSCs injections enhance periodontal regeneration, reverse the decrease in diversity, and increase the abundance of non-pathogenic bacterial Bifidobacterium sp. and Lactobacillus sp., making the oral microbiome similar to that of the PRE group. In vitro, PDLSCs inhibit the growth of Staphylococcus aureus, Escherichia coli, and Fusobacterium nucleatum. The main mechanism of action is postulated to involve production of the cationic antimicrobial peptide LL-37.ConclusionsOur findings reveal that PDLSC injections enhance periodontal regeneration and regulate the oral microbiome to foster an oral cavity microenvironment conducive to symbiotic microbiota associated with health.

Glioblastoma Multiforme: Sensitivity to Antimicrobial Peptides LL-37 and PG-1, and Their Combination with Chemotherapy for Predicting the Overall Survival of Patients.

Background/Objectives: Glioblastomas (GBMs) are the most malignant and intractable of all cancers, with an unfavorable clinical prognosis for affected patients. The objective was to analyze the sensitivity of GBM cells to the antimicrobial peptides (AMPs) cathelicidin (LL-37) and protegrin-1 (PG-1), both alone and in combination with chemotherapy, to predict overall survival (OS) in the patients. Methods: The study was conducted on 27 GBM patients treated in the neurosurgical department of the Almazov Medical Research Centre (Saint Petersburg, Russia) from 2021 to 2024. The cytotoxic effects of chemotherapy, AMPs, and their combinations on brain tumor cells were assessed by an MTT assay using a 50% inhibitory concentration (IC50). Results: In GBM cells from the patients, LL-37 and PG-1 exhibited strong anticancer effects, surpassing those of chemotherapy drugs. These LL-37 and PG-1 anticancer effects were associated with a statistically significant increase in life expectancy and OS in GBM patients. These findings were confirmed by experiments on rats with C6 glioma, where the intranasal administration of LL-37 (300 μM) and PG-1 (600 μM) increased the life expectancy of the animals to 69 and 55 days, respectively, compared to 24 days in the control group (HR = 4.139, p = 0.0005; HR = 2.542, p = 0.0759). Conclusions: Additionally, the combination of LL-37 and PG-1 with chemotherapy drugs showed that a high IC50 of LL-37 with cisplatin (cutoff > 800 μM) in GBM cells was associated with increased life expectancy (19 vs. 5 months, HR = 4.708, p = 0.0101) and OS in GBM patients. These combinations could be used in future GBM treatments.

Immunohistochemistry Study of Antimicrobial Peptides as a Future Diagnostic and Prognostic Tool for Periprosthetic Joint Infections.

Periprosthetic joint infection (PJI) is a reputable complication of arthroplasty surgery. Septic loosening is an implant biofilm-related infection with different characteristics and treatment than aseptic loosening. Misdiagnosing PJI results in choosing an inappropriate treatment and, in most cases, failure to achieve asepsis. The worldwide increase ofarthroplasty surgeries forces us to research more accurate ways to detect PJIs earlier, cheaper, and faster. In the current study, we investigated 52 arthroplasty revision surgeries (septic and aseptic) and, using immunohistochemistry staining of periprosthetic tissue, successfully demonstrated an important increase in antimicrobial peptides human β defensin-3 (HBD-3) and cathelicidin (LL-37) in the PJI group. Furthermore, we observed that patients with a positive LL-37 stain were associated with a more reserved prognosis at one-year follow-up. Thesepromising results suggest thatantimicrobial peptides HBD-3 and LL-37 could be used as future biomarkers for PJI detection.

Thermodynamic Study on Biomimetic Legionella gormanii Bacterial Membranes.

The presented studies were aimed at determining the interactions in model membranes (Langmuir monolayers) created of phospholipids (PL) isolated from Legionella gormanii bacteria cultured with (PL + choline) or without (PL - choline) choline and to describe the impact of an antimicrobial peptide, human cathelicidin LL-37, on PL's monolayer behavior. The addition of choline to the growth medium influenced the mutual proportions of phospholipids extracted from L. gormanii. Four classes of phospholipids-phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), cardiolipin (CL), and their mixtures-were used to register compression isotherms with or without the LL-37 peptide in the subphase. Based on them the excess area (Ae), excess (ΔGe), and total (ΔGm) Gibbs energy of mixing were determined. The thermodynamic analyses revealed that the PL - choline monolayer showed greater repulsive forces between molecules in comparison to the ideal system, while the PL + choline monolayer was characterized by greater attraction. The LL-37 peptide affected the strength of interactions between phospholipids' molecules and reduced the monolayers stability. Accordingly, the changes in interactions in the model membranes allowed us to determine the difference in their susceptibility to the LL-37 peptide depending on the choline supplementation of bacterial culture.

Combined release of LL37 peptide and zinc ion from a mussel-inspired coating on porous titanium for infected bone defect repairing

Implant-associated infections impose great burden on patient health and public healthcare. Antimicrobial peptides and metal ions are generally incorporated onto implant surface to deter bacteria colonization. However, it is still challenging to efficiently prevent postoperative infections at non-cytotoxic dosages. Herein, a scaffold based on porous titanium coated with a mussel-inspired dual-diameter TiO2 nanotubes is developed for loading dual drugs of LL37 peptide and Zn2+ with different sizes and characteristics. Benefiting from in-situ formed polydopamine layer and dual-diameter nanotubular structure, the scaffold provides an efficient platform for controllable drugs elution: accelerated release under acidic condition and sustained release for up to 28 days under neutral/alkalescent circumstances. Such combination of dual drugs simultaneously enhanced antibacterial efficacy and osteogenesis. In antibacterial test, LL37 peptide serving as bacteria membrane puncture agent, and Zn2+ acting as ROS generator, cooperatively destroyed bacterial membrane integrity and subsequently damaged bacterial DNA, endowing dual-drug loaded scaffold with remarkable bactericidal efficiency of > 92 % in vitro and > 99 % in vivo. Noteworthily, dual-drug loaded scaffold promoted bone-implant osteointegration under infectious microenvironment, overmatching single-drug load ones. It provides a promising strategy on surface modification of implant for infected bone defect repairing.

LL37-mtDNA regulates viability, apoptosis, inflammation, and autophagy in lipopolysaccharide-treated RLE-6TN cells by targeting Hsp90aa1.

Sepsis-induced acute lung injury is associated with lung epithelial cell injury. This study analyzed the role of the antimicrobial peptide LL37 with mitochondrial DNA (LL37-mtDNA) and its potential mechanism of action in lipopolysaccharide (LPS)-treated rat type II alveolar epithelial cells (RLE-6TN cells). RLE-6TN cells were treated with LPS alone or with LL37-mtDNA, followed by transcriptome sequencing. Differentially expressed and pivotal genes were screened using bioinformatics tools. The effects of LL37-mtDNA on cell viability, inflammation, apoptosis, reactive oxygen species (ROS) production, and autophagy-related hallmark expression were evaluated in LPS-treated RLE-6TN cells. Additionally, the effects of Hsp90aa1 silencing following LL37-mtDNA treatment were investigated in vitro. LL37-mtDNA further suppressed cell viability, augmented apoptosis, promoted the release of inflammatory cytokines, increased ROS production, and elevated LC3B expression in LPS-treated RLE-6TN cells. Using transcriptome sequencing and bioinformatics, ten candidate genes were identified, of which three core genes were verified to be upregulated in the LPS + LL37-mtDNA group. Additionally, Hsp90aa1 downregulation attenuated the effects of LL37-mtDNA on LPS-treated RLE-6TN cells. Hsp90aa1 silencing possibly acted as a crucial target to counteract the effects of LL37-mtDNA on viability, apoptosis, inflammation, and autophagy activation in LPS-treated RLE-6TN cells.

Biodistribution of the cationic host defense peptide LL-37 using SPECT/CT

Human cathelicidin LL-37, a cationic host defense peptide (CHDP), has several important physiological roles, including antimicrobial activity, immune modulation, and wound healing, and is a being investigated as a therapeutic candidate for several indications. While the effects of endogenously produced LL-37 are well studied, the biodistribution of exogenously administered LL-37 are less known. Here we assess the biodistribution of a gallium-67 labeled variant of LL-37 using nuclear imaging techniques over a 48 h period in healthy mice. When administered as an intravenous bolus just over 20 µg, the LL-37-based radiotracer was rapidly cleared from the blood, largely by the liver, while an appreciable fraction of the dose temporarily distributed to the lungs. When administered subcutaneously at the same dose level, the radiotracer was absorbed systemically following a two-phase kinetic model and was predominately cleared renally. Uptake into sites rich in immune cells, such as the lymph nodes and the spleen, was observed for both routes of administration. Scans of free gallium-67 were also performed as controls. Important preclinical insights into the biodistribution of exogenously administered LL-37 were gained from this study, which can aid in the understanding of this and related cationic host-defense peptides.

The effect of <i>Streptococcus mutans</i>, <i>Candida albicans</i> and other cariesogenic factors on the concentration of cathelicidin LL-37 in oral fluid in children with early childhood caries

BACKGROUND: Human antimicrobial peptides play a significant role in innate immunity. In the oral cavity salivary glands and mucosal epithelium produce human antimicrobial peptides, including defensins and cathelicidin LL-37. Cathelicidin is the most significant peptide protecting against different types of infections, controls the activity of commensal bacteria and prevents colonization and growth of pathogenic bacteria. AIM: To determine the concentration of cathelicidin LL-37 in the oral fluid of children 2–5 years old and the oral hygiene index depending on some of the parameters and intensity of the carious process in the oral cavity. MATERIALS AND METHODS: The study was conducted in a group of children aged 2-5 years old; the concentration of catelicidine in the oral fluid was determined by enzyme immunoassay. Moreover, the concentration of Streptococcus mutans in saliva, the presence of Candida albicans in dental plaque, oral hygiene index and the concentration of 25-hydroxycalciferol in venous blood were assessed in these children. RESULTS: The stydy revealed the dependence of the concentration of cathelicidin in the oral fluid on the intensity of the carious process in children as well as on the concentration of Streptococcus mutans in saliva, the presence of Candida albicans in plaque and poor oral hygiene. CONCLUSIONS: It was found that in children with high intensity of caries, the concentration of antimicrobial peptide LL-37 is twice lower than in children with low and medium intensity of early childhood caries.

Chitosan-coated liposomal systems for delivery of antibacterial peptide LL17-32 to Porphyromonas gingivalis

Periodontal disease is triggered by surface bacterial biofilms where bacteria are less susceptible to antibiotic treatment. The development of liposome-based delivery mechanisms for the therapeutic use of antimicrobial peptides is an attractive alternative in this regard. The cationic antimicrobial peptide LL-37 (human cathelicidin) is well-known to exert antibacterial activity against Porphyromonasgingivalis, a keystone oral pathogen. However, the antibacterial activity of the 16-amino acid fragment (LL17-32) of LL-37, is unknown. In addition, there are still gaps in studies using liposomal formulations as delivery vehicles of antibacterial peptides against this pathogen. This study was designed to examine the influence of the different types of liposomal formulations to associate and deliver LL17-32 to act against P. gingivalis. Chitosans of varying Mw and degree of acetylation (DA) were adsorbed at the surface of soya lecithin (SL) liposomes. Their bulk (average hydrodynamic size, ζ-potential and membrane fluidity) and ultrastructural (d-spacing, half-bilayer thickness and the water layer thickness) biophysical properties were investigated by a panel of techniques (DLS, SAXS, M3-PALS, fluorescence spectroscopy and TEM imaging). Their association efficiency, in vitro release, stability, and efficacy in killing the periodontal pathogen P. gingivalis were also investigated. All liposomal systems possessed spherical morphologies and good shelf-life stabilities. Under physiological conditions, chitosan formulations with a high DA demonstrated enhanced stability in comparison to low DA-chitosan formulations. Chitosans and LL17-32 both decreased SL-liposomal membrane fluidity. LL17-32 exhibited a high degree of association with SL-liposomes without in vitro release. In biological studies, free LL17-32 or chitosans alone, demonstrated microbicidal activity against P. gingivalis, however this was attenuated when LL17-32 was loaded onto the SL-liposome delivery system, presumably due to the restrained release of the peptide. A property that could be harnessed in future studies (e.g., oral mucoadhesive slow-release formulations).

Investigation of a novel bilayered PCL/PVA electrospun nanofiber incorporated Chitosan-LL37 and Chitosan-VEGF nanoparticles as an advanced antibacterial cell growth-promoting wound dressing

Chronic wounds have become a growing concern as they can have a profound impact on individuals, potentially resulting in mortality. It is crucial to prevent and manage bacterial infections, particularly drug-resistant ones. Antimicrobial peptides, such as LL-37, can firmly eliminate pathogens. Additionally, the process of angiogenesis, facilitated by growth factors like VEGF, is essential for tissue repair and wound healing. To enhance the stability and bioavailability of therapeutic agents, targeted delivery strategies utilizing Chitosan-based carriers have been employed. Electrospun biopolymers in advanced wound dressings have revolutionized wound care by providing a more effective and efficient solution for promoting tissue regeneration and speeding up the healing process. The present investigation utilized Chitosan nanoparticles to encapsulate the recombinant LL37 peptide and VEGF. An in-depth investigation was carried out to analyze the biophysical and morphological traits of the LL37-CSNPs and VEGF-CSNPs. The first support layer consisted of PCL electrospun nanofiber, followed by the electrospinning of PVA/CsLL37, PVA/CsVEGF, and PVA/CsLL37/CsVEGF onto the PCL layer. An in vitro examination assessed the fabricated nanofibers’ morphological, mechanical, and biological characteristics. The antimicrobial effects were tested on methicillin-resistant Staphylococcus aureus (MRSA). The in vivo experiments assessed the antibacterial and wound-healing capabilities of the nanofibers. The findings validated the continuous release of LL37 and VEGF. The composite material PCL/PVA/CsLL37/CsVEGF demonstrated potent bactericidal and antioxidant characteristics. The cytotoxic assay demonstrated the biocompatibility of the fabricated nano mats and their potential to accelerate fibroblast cell proliferation. The efficacy of PVA/CsLL37/CsVEGF in promoting wound healing was confirmed through an in vivo wound healing assay. Furthermore, the histological analysis provided evidence of faster epidermal formation and improved antibacterial activity in wounds covered with PVA/CsLL37/CsVEGF. Adding LL37 and VEGF to the composite material improves the immune response and promotes blood vessel formation, accelerating wound healing and decreasing inflammation.

Milk-derived extracellular vesicles functionalized with anti-tumour necrosis factor-α nanobody and anti-microbial peptide alleviate ulcerative colitis in mice.

Ulcerative colitis (UC) manifests clinically with chronic intestinal inflammation and microflora dysbiosis. Although biologics can effectively control inflammation, efficient delivery to the colon and colon epithelial cells remains challenging. Milk-derived extracellular vesicles (EV) show promise as an oral delivery tool, however, the ability to load biologics into EV presents challenges to therapeutic applications. Here, we demonstrate that fusing cell-penetrating peptide (TAT) to green fluorescent protein (GFP) enabled biologics loading into EV and protected against degradation in the gastrointestinal environment in vitro and in vivo after oral delivery. Oral administration of EV loaded with anti-tumour necrosis factor-α (TNF-α) nanobody (VHHm3F) (EVVHH) via TAT significantly reduced tissue TNF-α levels and alleviated pathologies in mice with acute UC, compared to VHH alone. In mice with chronic UC, simultaneously introducing VHH and an antimicrobial peptide LL37 into EV (EVLV), then administering orally improved intestinal barrier, inflammation and microbiota balance, resulted in relief of UC-induced depression and anxiety. Collectively, we demonstrated that oral delivery of EVLV effectively alleviated UC in mice and TAT efficiently loaded biologics into EV to confer protection from degradation in the gastrointestinal tract. This therapeutic strategy is promising for UC and is a simple and generalizable approach towards drug-loaded orally-administrable EV treatment for other diseases.

The effect of chitosan-furcellaran biopolymeric films and coatings incorporated with LL-37 and RW4 bioactive peptides on the microbiological and sensory quality of cheese

The study objective was to investigate the influence of chitosan-furcellaran films and coatings with bioactive peptides on cheese properties. The films were prepared using the casting method while the coatings by the dip-coating process. The yeast and mold count (YMC) was positive in the control Gouda after the 2nd week of storage. However, only after week 3 were yeast and mold detected in the samples covered with the RW4 film and in the coatings with no peptide or containing LL-37 (3.1–3.8 log cfu g−1). Regarding Mozzarella, a significant increase in YMC was determined after week 2 of storage in samples having coatings with no peptide or with LL-37 (6.2–6.3 log cfu g−1), whereas after the 1st week, YMC was increased in the control (6.6 log cfu g−1). The coatings with no peptide and with LL-37 demonstrated the best influence on microbiological quality, while having no negative impact on Gouda or Mozzarella sensory properties.

LL37 Microspheres Loaded on Activated Carbon-chitosan Hydrogel: Anti-bacterial and Anti-toxin Wound Dressing for Chronic Wound Infections.

Antimicrobial peptide LL37 is a promising antibacterial candidate due to its potent antimicrobial activity with no known bacterial resistance. However, intrinsically LL37 is susceptible to degradation in wound fluids limits its effectiveness. Bacterial toxins which are released after cell lysis are found to hinder wound healing. To address these challenges, encapsulating LL37 in microspheres (MS) and loading the MS onto activated carbon (AC)-chitosan (CS) hydrogel. This advanced wound dressing not only protects LL37 from degradation but also targets bacterial toxins, aiding in the healing of chronic wound infections. First, LL37 MS and LL37-AC-CS hydrogel were prepared and characterised in terms of physicochemical properties, drug release, and peptide-polymer compatibility. Antibacterial and antibiofilm activity, bacterial toxin elimination, cell migration, and cell cytotoxicity activities were investigated. LL37-AC-CS hydrogel was effective against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. LL37-AC-CS hydrogel bound more endotoxin than AC with CS hydrogel alone. The hydrogel also induced cell migration after 72h and showed no cytotoxicity towards NHDF after 72h of treatment. In conclusion, the LL37-AC-CS hydrogel was shown to be a stable, non-toxic advanced wound dressing method with enhanced antimicrobial and antitoxin activity, and it can potentially be applied to chronic wound infections to accelerate wound healing.

Correlation between Vitamin D Levels and Antimicrobial Peptide LL-37 in Pediatric Patients Diagnosed with Sepsis

Abstract Objective Our objective was to examine potential differences in inflammatory markers, specifically antimicrobial peptide (AMP) LL-37 and interleukin-6 (IL-6), in the bloodstream of children with sepsis who had varying levels of vitamin D3. Methods A total of 59 pediatric patients diagnosed with sepsis from January 2021 to November 2021 were enrolled in this study. The pediatric patients with sepsis were categorized into three groups based on their levels of vitamin D3, and AMP LL-37, IL-6, and procalcitonin (PCT) were compared among the three groups. Discussion The LL-37 level in the group with vitamin D3 deficiency was notably lower than in the other two groups (p deficiency group vs. insufficiency group = 0.019, p deficiency group vs. normal group = 0.034), whereas the disparity between the group with vitamin D3 insufficiency and the group with normal vitamin D3 levels was not statistically significant. There was a positive correlation between the level of vitamin D3 and LL-37 in pediatric patients with sepsis (r = 0.324, p = 0.012). On the other hand, the level of IL-6 in pediatric patients with sepsis showed a positive correlation with both LL-37 (r = 0.474, p = 0.000) and PCT (r = 0.527, p = 0.000). Conclusion Pediatric patients with sepsis typically exhibit low levels of vitamin D3, which are positively correlated with the levels of serum LL-37. Furthermore, the presence of higher levels of serum LL-37 is positively correlated with higher levels of IL-6.

37. Plasma Level of the Antimicrobial Peptide LL37 (Cathelicidin) is Negatively Associated With Alcohol Use Disorder in US Veterans

37. Plasma Level of the Antimicrobial Peptide LL37 (Cathelicidin) is Negatively Associated With Alcohol Use Disorder in US Veterans