The potential of nitric oxide releasing therapies as antimicrobial agents

High-dose inhaled NO for the prevention of nosocomial pneumonia after cardiac surgery under cardiopulmonary bypass: A proof-of-concept prospective randomised study

OBJECTIVE

This study aimed to assess the safety and potential efficacy of high-dose inhaled nitric oxide therapy for the prevention of postoperative pneumonia in cardiac surgery patients.

METHODS

A prospective randomised controlled pilot study included 74 patients with moderate risk of postoperative pneumonia after elective cardiac surgery under cardiopulmonary bypass. Patients were randomised into two groups. The main group (NO-group) (n = 37) received inhaled nitric oxide at a dose of 200 ppm for 30 minutes 2 times a day for 5 days or until pneumonia developed. The control group received conventional postoperative care (n = 37). The primary endpoint was the incidence of postoperative pneumonia during in-hospital stay.

RESULTS

Preventive nitric oxide inhalations were associated with a reduced incidence of postoperative nosocomial pneumonia (2 (5.4%) cases in the main group (NO-group) vs. 9 (24.3%) cases in the control group, p = 0.046; OR = 0.178, 95% CI = 0.036-0.89)). There was no decrease in either peak expiratory flow, or peak inspiratory flow in comparison with the preoperative values in the NO-group. Inhaled nitric oxide therapy is safe. It did not lead to an increase in the incidence of acute kidney injury.

CONCLUSIONS

High-dose inhaled nitric oxide therapy is safe and effective for the prevention of postoperative nosocomial pneumonia in cardiac surgery.

Nitric oxide: a gas transmitter in healthy and diseased skin

Numerous physiological processes in the human skin are mediated by nitric oxide, a gaseous signalling molecule. Almost every type of skin cell may produce nitric oxide, it is possible to generate nitric oxide without the need of enzymes. Nitric oxide plays a crucial role in regulating apoptosis, keratinocyte differentiation and proliferation, the protective properties of the epidermal barrier, and the structure and functions of the microcirculatory bed. Nitric oxide is involved in immunological and inflammatory responses, hair growth regulation, and wound healing processes. It mediates ultraviolet-induced processes such as erythema and edema development and participates in melanogenesis. Furthermore, the ability of nitric oxide to bind reactive oxygen species and prevent lipid peroxidation gives it antioxidant qualities. This coordinated action of nitric oxide on gene expression and membrane integrity effectively protects cells from ultraviolet A-induced apoptosis and necrosis. Furthermore, nitric oxide can be considered as a molecule that inhibits the development of cancer and photoaging. It directly harms microorganisms and indirectly activates the immune system, exhibiting antibacterial, antiviral, and antifungal qualities. Notably, nitric oxide is effective against antibiotics-resistant bacteria. All of the aforementioned findings suggest that nitric oxide is a gaseous mediator that can protect skin function.

Multifunctional slippery nanoemulsion-infused porous nitric oxide-releasing surfaces

The need for biocompatible materials for medical devices remains critical, as complications such as infection, thrombosis, and biofouling significantly contribute to medical device failure and patient morbidity and mortality. In recent years, nitric oxide (NO)-releasing technologies have been explored to mitigate bacterial infections, particularly those stemming from common gram-positive and gram-negative bacterial pathogens. However, NO-releasing materials do not inherently possess anti-fouling capabilities. Combination strategies that use NO and anti-fouling surfaces (e.g., slippery lubricant-infused porous surfaces) have been explored to compensate for the deficit. In this work, a novel material was developed and assessed that combines the antibacterial capabilities of a NO-releasing substrate with the anti-fouling effects of a nanoemulsion (NE)-infused slippery surface. Using a covalently bound NO donor (S-nitroso-N-acetylpenicillamine, SNAP) to poly(dimethylsiloxane) (PDMS) and infused with a NE, denoted as SNAP-PDMS-NE, the NO release was sustained for 7 days. In addition to the prolonged NO release, the infused NE layer maintained a slippery nature and sliding angle below 20° for 7 days. The reported NO-releasing NE-swelled surface efficiently reduced Staphylococcus aureus adhesion by 3.5 log and Escherichia coli adhesion by 1.5 log after 24 h, reduced platelet adhesion by 89.92 %, and remained cytocompatible with relative cell viability greater than 70 %.

L-Arginine and immune modulation: A pharmacological perspective on inflammation and autoimmune disorders

L- Arginine (2-Amino-5-guanidinovaleric acid, L-Arg) is a semi-essential amino acid that is mainly produced within the urea cycle. It acts as a key precursor in the synthesis of proteins, urea, creatine, prolamines (including putrescine, spermine, and spermidine), proline, and nitric oxide (NO). WhenL-Arg is metabolized, it produces NO, glutamate, and prolamines, which all play important regulatory roles in various physiological functions. In addition to its metabolic roles,L-Arg significantly influences immune responses, especially in the context of inflammation and autoimmune diseases. It affects the activity of immune cells by modulating T-cell function, the polarization of macrophages, and the release of cytokines. Importantly,L-Arg plays a dual role in immune regulation, functioning as both an immunostimulatory and immunosuppressive agent depending on the specific cellular and biochemical environments. This review examines the immunopharmacological mechanisms of L-Arg, emphasizing its involvement in inflammatory responses and its potential therapeutic uses in autoimmune conditions like rheumatoid arthritis, multiple sclerosis, and inflammatory bowel disease. By influencing the pathways of nitric oxide synthase (NOS) and arginase (ARG), L-Arg helps maintain immune balance and contributes to the pathophysiology of diseases. Gaining a better understanding of the pharmacological effects of L-Arg on immune regulation could yield new perspectives on targeted treatments for immune-related diseases. Exploring its impact on immune signaling and metabolic pathways may result in novel therapeutic approaches for chronic inflammatory and autoimmune disorders.

Nitric Oxide-Releasing Liposomes for Treatment of Mycobacterium abscessus Infections

Nontuberculosis mycobacteria (NTM) are ubiquitous, opportunistic pathogens that cause severe respiratory infection, primarily in elderly and immunocompromised populations. The second most prevalent NTM pathogen, Mycobacterium abscessus, is considered the most refractory due to its fast growth rate, intracellular survivability, and antibiotic resistance. Treatments are thus sparse and generally ineffective, promoting antibiotic resistance upon chronic use. Nitric oxide (NO) is an endogenously produced free radical that exerts antimicrobial effects against pathogens via several mechanisms of action, and as such, it is unlikely to elicit resistance. Methyl tris diazeniumdiolate (MD3) is a small-molecule NO-releasing prodrug that is capable of sustained NO release, making it an attractive candidate as an antimicrobial therapeutic; however, its triple negative charge makes cellular uptake unlikely. As liposomes enable cellular uptake, their use as an MD3 delivery system may further enhance the utility of NO release for treating intracellular NTM infections. Herein, liposomal formulations were evaluated as a function of pH and buffer composition and optimized for MD3 loading to enable the delivery of bactericidal levels of NO. Planktonic studies with two clinically relevant morphotypes of M. abscessus revealed that lower pKa liposomal systems employ a better antimicrobial efficacy. Prevention and eradication assays revealed that liposomal MD3 significantly improves biofilm inhibition compared to nonliposomal MD3 and was capable of eradicating biofilm bacteria at 4 mg mL-1. Liposomal MD3 and MD3 had similar reductions in intracellular bacterial load, achieving at least a three-log reduction at relevant concentrations. Fluorescence spectroscopy over 24 h demonstrated that liposomal encapsulation increased the intracellular concentration of a membrane-impermeable fluorophore by 3.4-fold. Confocal microscopy was used to visualize the increase in the number of cells containing intracellular NO and the sustained presence of NO within the cell, confirming that liposomal MD3 increases small-molecule internalization.

S-Nitrosylated Au@COF nanohybrids for synergistic light-nitric oxide killing of bacteria

Nanohybrids integrating plasmonic Au and NO donors have been synthesized by a COF-mediated strategy, which effectively eradicate bacteria and biofilms, via mild phototherapy synergized with controlled NO release and ONOO- generation.

Antimicrobial nitric oxide releasing gelatin nanoparticles to combat drug resistant bacterial and fungal infections

Antimicrobial resistance (AMR) represents a significant global health challenge, contributing to increased mortality rates and substantial economic burdens. The development of new antimicrobial agents with dual antimicrobial and antibiofilm capabilities is crucial to mitigate AMR. Nitric oxide (NO) is a broad-spectrum antimicrobial agent which has shown promise in treating infections due to its multiple antimicrobial mechanisms. However, the high reactivity of NO poses a challenge for effective delivery to infection sites. We investigated the antimicrobial and antibiofilm capabilities, and the shelf life, of NO-releasing gelatin nanoparticles (GNP/NO) against three common hospital-acquired pathogens: Staphylococcus aureus, Escherichia coli, and Candida albicans. The synthesised GNP/NO were found to be cytocompatible and exhibited significant antimicrobial and antibiofilm efficacies against the tested pathogens in both nutrient-rich and nutrient-poor conditions. Furthermore, we found that the antimicrobial capabilities of GNP/NO were maintained for up to 6 months post synthesis, against Staphylococcus aureus (2.4 log), Escherichia coli (1.2 log) and Candida albicans (3 log) under nutrient-poor conditions. Our study demonstrates the use of a novel broad-spectrum antimicrobial with a prolonged shelf life for the treatment of infections. These findings offer an effective alternative to traditional antibiotics which would contribute to mitigating the current global AMR threat resulting from antibiotic overuse.

Nitric Oxide-Mediated Dual-Functional Smart Titanium Implant Coating for Antibacterial and Osseointegration Promotion in Implant-Associated Infections

The balance of antibacterial and osseointegration-promoting properties on titanium (Ti) implants in a simple and efficient manner is crucial for the management of implant-associated infections, a condition that has become a significant global health concern. Herein, a nitric oxide (NO)-mediated dual-function smart coating with antibacterial and osseointegration-promoting properties is developed for Ti implants. The coating leverages the distinct properties of NO at high and low concentrations to enable an on-demand functional switch. Specifically, antibacterial function is achieved through a rapid release of high-dose NO in response to the infection microenvironment and near-infrared stimulation. Once the infection is resolved and normal physiological conditions are restored, the coating gradually releases low-dose NO to promote osseointegration. In vitro tests confirm that the coating exhibits antibacterial ratio of 97.84% and 97.18% against methicillin-resistant Staphylococcus aureus and its biofilms, respectively, and demonstrates the ability to activate osteoblasts. The rat femoral implant-associated infection model further certifies that the responsive NO release mechanism of the coating efficiently facilitates the on-demand functional switch between antibacterial and osseointegration-promoting properties. Notably, the use of the dual-functional nonantibiotic agent, NO, significantly mitigates the risk of bacterial resistance.

Reactive Oxygen Species and Antioxidants in Wound Healing: Mechanisms and Therapeutic Potential

Wound healing is a complex biological process encompassing haemostasis, inflammation, proliferation and matrix remodelling. Reactive oxygen species (ROS) play a pivotal role in regulating key events such as antimicrobial defence, platelet activation and angiogenesis. However, excessive ROS levels can induce oxidative stress (OS), disrupting the healing cascade and contributing to chronic wounds, inflammation and impaired tissue repair. Systemic conditions like diabetes, obesity, smoking and ageing further exacerbate OS, highlighting its clinical significance in wound management. Antioxidants (AOx), both endogenous and exogenous, have demonstrated therapeutic potential in mitigating OS, promoting wound closure and enhancing cellular recovery. Compounds like Vitamin E, curcumin, ferulic acid and resveratrol improve AOx enzyme activity, reduce oxidative damage and accelerate wound healing in multiple studies. Emerging evidence supports targeting oxidative pathways as a viable strategy to improve outcomes in chronic and systemic OS-related conditions. This review explores the dual role of ROS in wound healing, the impact of OS in systemic diseases, and the therapeutic potential of AOx in fostering optimal healing outcomes, advocating for robust clinical trials to establish standardised interventions.

Nitric oxide synthases: A delicate dance between bone regeneration and neuronal birth

Spinal cord injury (SCI) is a devastating condition resulting from traumatic or nontraumatic injury/chronic disorder. The pathogenesis of SCI necessitates a comprehensive approach, as it involves therapeutic strategies addressing both bone (spine) and neural (spinal cord) damage. This review centers on the pivotal role of nitric oxide (NO) and its synthesizing enzymes, nitric oxide synthases (NOS), in mediating the crosstalk between osteogenesis and neurogenesis. NO's effects are context-dependent, exhibiting a delicate balance between beneficial and detrimental actions. Reduced levels of nitric oxide (NO), primarily derived from endothelial NOS (eNOS), tipically stimulate osteoblast activity and promote neurogenesis by influencing neural stem cell (NSC) migration and differentiation. Conversely, elevated NO levels, predominantly from inducible NOS (iNOS), tipically triggered by inflammation, inhibit both processes through pro-apoptotic mechanisms. Nevertheless, these phenomena are not merely simplistic; they can be influenced by a variety of other factors. We explore the intricate interplay of NO/NOS with key signaling pathways crucial in neurogenesis and osteogenesis, including mechanical stimuli, Wnt, interleukins, BMPs, NF-κB, etc., revealing their influence on neuroinflammation, neurogenesis, and osteoblast differentiation. The temporal and spatial dynamics of NO/NOS activity and the implications for therapeutic intervention have been discussed. Precise modulation of NO levels and NOS isoforms, potentially through targeted therapies manipulating these interacting signaling pathways, emerges as a promising strategy for promoting bone and neural regeneration. This review highlights the critical need for a balanced approach in therapeutic strategies to harness the beneficial effects of NO/NOS while mitigating its detrimental consequences.

Efficacy of a Topical Nitric Oxide-Releasing Gel on Polymicrobial Wound Infections

INTRODUCTION

Wounds are colonized frequently by heterogeneous microflora. Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) are two of the most isolated bacterial species from wounds, and both typically form highly organized biofilms. Nitric oxide (NO) is a short-lived, diatomic, lipophilic gas with antimicrobial activity. Recently, NO and its derivatives have been shown to exhibit broad-spectrum antimicrobial activity against bacteria, viruses, and parasites.

MATERIALS AND METHODS

P. aeruginosa strain ATCC 27312 or military isolate PA09-010 were combined with methicillin-resistant S. aureus strain MRSA USA300 to demonstrate the ability of NO to reduce polymicrobial infections in a porcine wound infection model. Deep partial-thickness wounds (10 mm × 7 mm × 0.5 mm) were made on four animals using a specialized electrokeratome. Wounds were inoculated with MRSA USA300 combined with PA09-010 in three animals and MRSA USA300 combined with PA27312 in one animal, then wounds were covered with polyurethane film dressings. After 48 hours, three wounds were recovered for baseline enumeration. The remaining wounds were randomly assigned to treatment groups and treated once daily. The NO topical gels tested were combinations of two phases, ointment phases with various concentrations (2-20%) combined with hydrogels with fast or slow release kinetics. A 4-day study with microbiological recovery was conducted on day 4. A separate 7-day study was also conducted, with microbial burden assessed on day 7.

RESULTS

The largest efficacy against MRSA USA300 was observed for the NO formulation with 2% concentration and fast release kinetics. This treatment reduced the MRSA USA300 bacterial count by more than 99.97% and 99.95% from baseline in wounds co-infected with PA09-010 and PA 27312, respectively, at day 7. Treatments showed a minimal efficacy against PA27312 and PA09-010 strains in both assessment times. MRSA USA300 was reduced to a lesser extent when it was combined with PA27312 as compared to PA09-010.

CONCLUSIONS

These studies demonstrate that NO-releasing topical formulations effectively reduce the MRSA burden in established biofilms composed of multiple microorganisms. Minimal efficacy against PA was observed. It has been demonstrated that MRSA bioburden is significantly reduced when inoculated together with P. aeruginosa. A better understanding of mechanisms of host-bacteria interactions, in single or mixed species biofilms, may lead to the development of novel therapeutic approaches. Overall, NO offers a promising alternative treatment against MRSA in polymicrobial infections.

Antibiotic-Resistant Pseudomonas aeruginosa: Current Challenges and Emerging Alternative Therapies

Antibiotic-resistant Pseudomonas aeruginosa is a pathogen notorious for its resilience in clinical settings due to biofilm formation, efflux pumps, and the rapid acquisition of resistance genes. With traditional antibiotic therapy rendered ineffective against Pseudomonas aeruginosa infections, we explore alternative therapies that have shown promise, including antimicrobial peptides, nanoparticles and quorum sensing inhibitors. While these approaches offer potential, they each face challenges, such as specificity, stability, and delivery, which require careful consideration and further study. We also delve into emerging alternative strategies, such as bacteriophage therapy and CRISPR-Cas gene editing that could enhance targeted treatment for personalized medicine. As most of them are currently in experimental stages, we highlight the need for clinical trials and additional research to confirm their feasibility. Hence, we offer insights into new therapeutic avenues that could help address the pressing issue of antibiotic-resistant Pseudomonas aeruginosa, with an eye toward practical applications in future healthcare.

Nitric Oxide Inhibition of Glycyl Radical Enzymes and Their Activases

Innate immune response cells produce high concentrations of the free radical nitric oxide (NO) in response to pathogen infection. The antimicrobial properties of NO include nonspecific damage to essential biomolecules and specific inactivation of enzymes central to aerobic metabolism. However, the molecular targets of NO in anaerobic metabolism are less understood. Here, we demonstrate that the Escherichia coli glycyl radical enzyme pyruvate formate lyase (PFL), which catalyzes the anaerobic metabolism of pyruvate, is irreversibly inhibited by NO. Using electron paramagnetic resonance and site-directed mutagenesis we show that NO destroys the glycyl radical of PFL. The activation of PFL by its cognate radical S-adenosyl-l-methionine-dependent activating enzyme (PFL-AE) is also inhibited by NO, resulting in the conversion of the essential iron-sulfur cluster to dinitrosyl iron complexes. Whole-cell EPR and metabolic flux analyses of anaerobically growing E. coli show that PFL and PFL-AE are inhibited by physiologically relevant levels of NO in bacterial cell cultures, resulting in diminished growth and a metabolic shift to lactate fermentation. The class III ribonucleotide reductase (RNR) glycyl radical enzyme and its corresponding RNR-AE are also inhibited by NO in a mechanism analogous to those observed in PFL and PFL-AE, which likely contributes to the bacteriostatic effect of NO. Based on the similarities in reactivity of the PFL/RNR and PFL-AE/RNR-AE enzymes with NO, the mechanism of inactivation by NO appears to be general to the respective enzyme classes. The results implicate an immunological role of NO in inhibiting glycyl radical enzyme chemistry in the gut.

Evaluation of salivary nitric oxide levels and anxiety in multiple sclerosis patients, with and without Xerostomia: correlation with clinical variables

BACKGROUND

Xerostomia is a prevalent but often overlooked condition in multiple sclerosis (MS) patients, significantly impacting their quality of life and oral health. This cross-sectional observational study investigates the role of nitric oxide (NO) in the pathophysiology of multiple sclerosis (MS) and explores its association with xerostomia in MS patients. The primary objective was to compare salivary NO concentrations and stress levels between MS patients with and without xerostomia.

METHODS

MS patients diagnosed by neurologists and MRI were categorized into two groups: those with xerostomia and those without. Unstimulated whole saliva samples were collected using the spitting method, and salivary NO levels were quantified using an enzyme-linked immunosorbent assay (ELISA) kit based on the Griess reaction. Stress levels were assessed using the Beck Anxiety Inventory (BAI) questionnaire. The presence of xerostomia was evaluated through the Xerostomia Inventory (XI) and clinical examinations.

RESULTS

Salivary NO levels were significantly higher in MS patients without xerostomia (227.47 ng/mL) compared to those with xerostomia (102.37 ng/mL, p < 0.001). Stress levels were also notably higher in MS patients with xerostomia (17.23) versus those without (11.77, p = 0.03). A moderate negative correlation was observed between salivary NO levels and xerostomia (r = 0.44, p < 0.001), indicating that lower NO levels were associated with a higher likelihood of xerostomia. The correlation between stress levels and xerostomia was weaker but still significant (r = 0.28, p = 0.03). Multivariate binary logistic regression analysis identified salivary NO, stress levels, and age as significant predictors of xerostomia in MS patients. The logistic regression model achieved an 80% accuracy in predicting xerostomia based on salivary NO levels and stress.

CONCLUSION

This study highlights a significant negative correlation between salivary NO levels and xerostomia, suggesting that decreased salivary NO concentrations are associated with an increased risk of xerostomia in MS patients. Additionally, stress levels were positively correlated with xerostomia, indicating a potential link between higher stress and the likelihood of xerostomia in MS patients.

Role of Pseudomonas aeruginosa Dnr-regulated denitrification in oxic conditions

Pseudomonas aeruginosa causes acute and chronic infections such as those that occur in the lungs of people with cystic fibrosis (CF). In infection environments, oxygen (O 2 ) concentrations are often low. The transcription factor Anr responds to low O 2 by upregulating genes necessary for P. aeruginosa fitness in microoxic and anoxic conditions. Anr regulates dnr , a gene encoding a transcriptional regulator that promotes the expression of genes required for using nitrate as an alternative electron acceptor during denitrification. In CF sputum, transcripts involved in denitrification are highly expressed. While Dnr is necessary for the anoxic growth of P. aeruginosa in CF sputum and artificial sputum media (ASMi), the contribution of denitrification to P. aeruginosa fitness in oxic conditions has not been well described. Here we show that P. aeruginosa requires dnr for fitness in ASMi and the requirement for dnr is abolished when nitrate is excluded from the media. Additionally, we show that P. aeruginosa consumes nitrate in lysogeny broth (LB) under microoxic conditions. Furthermore, strains without a functioning quorum sensing regulator LasR, which leads to elevated Anr activity, consume nitrate in LB even in normoxia. There was no growth advantage for P. aeruginosa when nitrate was present at concentrations from 100 µM to 1600 µM. However, P. aeruginosa consumption of nitrate in oxic conditions created a requirement for Dnr and Dnr-regulated NorCB likely due to the need to detoxify nitric oxide. These studies suggest that Anr- and Dnr-regulated processes may impact P. aeruginosa physiology in many common culture conditions.

Importance

Pseudomonas aeruginosa is an opportunistic pathogen commonly isolated from low-oxygen environments such as the lungs of people with cystic fibrosis. While the importance of P. aeruginosa energy generation by denitrification is clear in anoxic environments, the effects of denitrification in oxic cultures is not clear. Here, we show that nitrate is consumed even in oxic environments and while it does not appear to stimulate growth, it does impact fitness. Further, we report that two regulators that are best known for their roles in anoxic conditions also contribute to P. aeruginosa fitness in commonly- used laboratory media in presence of oxygen.

Impact of intragastric administration of donkey milk on mouse immunity utilizing gut microbiomics and plasma metabolomics

Introduction

Donkey milk demonstrates closer compositional resemblance to human milk compared to bovine milk, positioning it as an optimal nutritional substitute for infants with cow's milk allergy. Furthermore, its rich profile of bioactive compounds suggests potential immunomodulatory properties. This study systematically investigated the effects of donkey milk supplementation on murine immune function and gut microbiome dynamics, thereby providing mechanistic insights to support its clinical development in functional food applications.

Methods

Following daily intragastric administration of 10 mL/kg of body weight of donkey milk (DM) or distilled water (DW) to the mice for 28 consecutive days, liver tissues were harvested for immunological profiling, with concurrent collection of blood samples for plasma metabolomic analysis and fecal specimens for gut microbiome characterization. Subsequently, the modulatory effects of donkey milk supplementation on immune parameters, intestinal microbiota composition, and plasma metabolic profiles were systematically evaluated.

Results

Immunity analysis revealed that intragastric administration of DM raised the levels of IL-6 and TNF-α cytokines in mouse liver. In addition, DM modulated the composition of both the murine gut microbiome and plasma metabolites. One-hundred and forty-five differentially-produced metabolites were identified, most prominently nicotinamide, L-valine, and β-estradiol, that are primarily associated with valine, leucine, and isoleucine biosynthesis and degradation, nicotinate and nicotinamide metabolism, and unsaturated fatty acid biosynthesis. Alterations at phylum, genus, and species levels were evident in the fecal microbiota of mice after intragastric administration of DM. In particular, an increased abundance of the Lactobacillus bacterium was observed. Correlation analysis of differential metabolites and microbiomes indicated a correspondence between Falsiroseomonas and Salipiger species and the antioxidant coenzyme Q that has the potential to activate the immune system.

Conclusion

The data collectively suggest that DM may adjust the murine gut microbiome and plasma metabolites thereby potentially improving immunity in mice.

Nano-enhanced benzylpenicillin: Bridging antibacterial action with anti-inflammatory potential against antibiotic-resistant bacteria

This study investigates the enhancement of benzylpenicillin's antibacterial properties using nanomedicine, specifically by developing benzylpenicillin nanoemulsions. To address the escalating issue of bacterial resistance, we employed the advanced techniques Raman spectroscopy and atomic force microscopy to analyze the nanoemulsions' molecular structure and characteristics. We then evaluated the impact of these nanoemulsions on nitric oxide production by macrophages to deternine their potential to modulate inflammatory responses. We further assessed the antibacterial effectiveness of the nanoparticles against the pathogens Streptococcus pyogenes (Group A Streptococcus) and Streptococcus agalactiae (Group B Streptococcus). The results of antibiograms showed significant efficacy against Gram-positive bacteria, with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values, confirming their bactericidal potential. The investigation into the mechanism of action suggested substantial disruption to bacterial membrane integrity, underscoring a possible mode of antibacterial activity. Overall, the study provides valuable insights into the synergistic relationship between antibiotics and nanoparticles. In particular, it demonstrates the potential of benzylpenicillin nanoparticles to enhance the antimicrobial efficacy and influence inflammatory responses obtained by evaluating nitrite, IL-6 and TNF-α, offering promising avenues for future clinical applications and strategies to combat bacterial resistance.

Nitric Oxide Inhibition of Glycyl Radical Enzymes and Their Activases

Innate immune response cells produce high concentrations of the free radical nitric oxide (NO) in response to pathogen infection. The antimicrobial properties of NO include non-specific damage to essential biomolecules and specific inactivation of enzymes central to aerobic metabolism. However, the molecular targets of NO in anaerobic metabolism are less understood. Here, we demonstrate that the Escherichia coli glycyl radical enzyme pyruvate formate lyase (PFL), which catalyzes the anaerobic metabolism of pyruvate, is irreversibly inhibited by NO. Using electron paramagnetic resonance and site-directed mutagenesis we show that NO destroys the glycyl radical of PFL. The activation of PFL by its cognate radical S-adenosyl-L-methionine-dependent activating enzyme (PFL-AE) is also inhibited by NO, resulting in the conversion of the essential iron-sulfur cluster to dinitrosyl iron complexes. Whole-cell EPR and metabolic flux analyses of anaerobically growing Escherichia coli show that PFL and PFL-AE are inhibited by physiologically relevant levels of NO in bacterial cell cultures, resulting in diminished growth and a metabolic shift to lactate fermentation. The class III ribonucleotide reductase (RNR) glycyl radical enzyme and its corresponding RNR-AE are also inhibited by NO in a mechanism analogous to those observed in PFL and PFL-AE, which likely contributes to the bacteriostatic effect of NO. Based on the similarities in reactivity of the PFL/RNR and PFL-AE/RNR-AE enzymes with NO, the mechanism of inactivation by NO appears to be general to the respective enzyme classes. The results implicate an immunological role of NO in inhibiting glycyl radical enzyme chemistry in the gut.

The impacts of thermal stress on dairy cattle physiology, metabolism, health, and performance: a comprehensive review

Climate change is becoming a global issue, with important implications for dairy cow performance and well-being. It is distinguished by a gradual rise in universal temperature and the risk of extreme weather occurrences. Studies have shown that heat stress (HS) impacts many biological processes that can have significant economic issues. Due to their elevated metabolic rate, cows are mostly liable to HS, which negatively affects immune function, particularly cell-mediated immune response, and subsequent reduced production performance and inferior immunity, which leads to elevated susceptibility to disease, increased incidence of intramammary infections, and an elevated somatic cell count, as well as calf mortality, particularly during the summer season. Furthermore, dry cows subjected to HS had reduced immunoglobulin levels after vaccination, although this impact fades with cooling after parturition. On the other hand, cows subjected to HS while dry demonstrate carryover impacts on the innate arm of the immunity in early lactation, resulting in losses. Heat mitigation technologies are cost-effective and necessary for sustaining milk production and the dairy farm’s profitability. Furthermore, a check of present HS mitigation measures is required to understand better and identify acceptable abatement plans for future stress management.

Engineering Gas-Releasing Nanomaterials for Efficient Wound Healing

The escalating prevalence of tissue damage and its associated complications has elicited global apprehension. While nanomaterial-based wound healing exhibits significant potential in terms of curbing infections and surpassing conventional methods, unresolved concerns regarding nanomaterial controllability and precision remain unresolved, jeopardizing its practical applications. In recent years, a unique strategy for creating gas-releasing nanomaterials for wound repair has been proposed, involving the creation of gas-releasing nanomaterials to facilitate wound repair by generating gas donor moieties. The operational spatiotemporal responsiveness and broad-spectrum antibacterial properties of these gases, combined with their inability to generate bacterial resistance like traditional antibiotics, establish their efficacy in addressing chronic non-healing wounds, specifically diabetic foot ulcers (DFUs). In this review, we delve into the intricacies of wound healing process, emphasizing the chemical design, functionality, bactericidal activity, and potential of gas-release materials, encompassing NO, CO, H2S, O2, CO2, and H2, for effective wound healing. Furthermore, we explore the advancements in synergistic therapy utilizing these gases, aiming to enhance our overall comprehension of this field. The insights gleaned from this review will undoubtedly aid researchers and developers in the creation of promising gas-releasing nanomaterials, thus propelling efficient wound healing in the future.

Choroid plexus organoids reveal mechanisms of Streptococcus suis translocation at the blood-cerebrospinal fluid barrier

Streptococcus suis is a globally emerging zoonotic pathogen that can cause invasive disease commonly associated with meningitis in pigs and humans. To cause meningitis, S. suis must invade the central nervous system (CNS) by crossing the neurovascular unit, also known as the blood-brain barrier (BBB), or vascularized choroid plexus (ChP) epithelium known as the blood-cerebrospinal fluid barrier (BCSFB). Recently developed ChP organoids have been shown to accurately replicate the cytoarchitecture and physiological functions of the ChP epithelium in vivo. Here, we used human induced pluripotent stem cells (iPSC)-derived ChP organoids as an in vitro model to investigate S. suis interaction and infection at the BCSFB. Our study revealed that S. suis is capable of translocating across the epithelium of ChP organoids without causing significant cell death or compromising the barrier integrity. Plasminogen (Plg) binding to S. suis in the presence of tissue plasminogen activator (tPA), which converts immobilized Plg to plasmin (Pln), significantly increased the basolateral to apical translocation across ChP organoids into the CSF-like fluid in the lumen. S. suis was able to replicate at the same rate in CSF and laboratory S. suis culture medium but reached a lower final density. The analysis of transcriptomes in ChP organoids after S. suis infection indicated inflammatory responses, while the addition of Plg further suggested extracellular matrix (ECM) remodeling. To our knowledge, this is the first study using ChP organoids to investigate bacterial infection of the BCSFB. Our findings highlight the potential of ChP organoids as a valuable tool for studying the mechanisms of bacterial interaction and infection of the human ChP in vitro.

Emerging strategies for nitric oxide production and their topical application as nanodressings to promote diabetic wound healing

The challenges associated with prolonged healing or non-healing of chronic diabetic wounds contribute significantly to the increased incidence of lower limb amputation. A pivotal factor in the impediment of healing is the reduced production of endogenous nitric oxide (NO) due to the hyperglycemic microenvironment typical of chronic diabetes. While both endogenous and exogenous NO have been shown to promote the healing process of diabetic wounds, the direct application of NO in wound management is limited due to its gaseous nature and the risk of explosive release. This review summarizes recent advances of nanodressings incorporating NO donors in the treatment of diabetic wounds, detailing the specific conditions under which these nanodressings facilitate NO release, with a focus on the beneficial effects of NO, strategies for its supplementation, and the challenges encountered in the clinical translation of NO donors as a clinically viable nanomedicine in the context of improving diabetic wound healing.

BiomiX, a user-friendly bioinformatic tool for democratized analysis and integration of multiomics data

BACKGROUND

Interpreting biological system changes requires interpreting vast amounts of multi-omics data. While user-friendly tools exist for single-omics analysis, integrating multiple omics still requires bioinformatics expertise, limiting accessibility for the broader scientific community.

RESULTS

BiomiX tackles the bottleneck in high-throughput omics data analysis, enabling efficient and integrated analysis of multiomics data obtained from two cohorts. BiomiX incorporates diverse omics data, using DESeq2/Limma packages for transcriptomics, and quantifying metabolomics peak differences, evaluated via the Wilcoxon test with the False Discovery Rate correction. The metabolomics annotation for Liquid Chromatography-Mass Spectrometry untargeted metabolomics is additionally supported using the mass-to-charge ratio in the CEU Mass Mediator database and fragmentation spectra in the TidyMass package. Methylomics analysis is performed using the ChAMP R package. Finally, Multi-Omics Factor Analysis (MOFA) integration identifies shared sources of variation across omics data. BiomiX also generates statistics, report figures and integrates EnrichR and GSEA for biological process exploration and subgroup analysis based on user-defined gene panels enhancing condition subtyping. BiomiX fine-tunes MOFA models, to optimize factors number selection, distinguishing between cohorts and providing tools to interpret discriminative MOFA factors. The interpretation relies on innovative bibliography research on Pubmed, which provides the articles most related to the discriminant factor contributors. Furthermore, discriminant MOFA factors are correlated with clinical data, and the top contributing pathways are explored, all with the aim of guiding the user in factor interpretation.

CONCLUSIONS

The analysis of single-omics and multi-omics integration in a standalone tool, along with MOFA implementation and its interpretability via literature, represents significant progress in the multi-omics field in line with the "Findable, Accessible, Interoperable, and Reusable" data principles. BiomiX offers a wide range of parameters and interactive data visualization, allowing for personalized analysis tailored to user needs. This R-based, user-friendly tool is compatible with multiple operating systems and aims to make multi-omics analysis accessible to non-experts in bioinformatics.

The efficacy of a nitric oxide-releasing formulation on nares isolated Methicillin-Resistant Staphylococcus aureus in porcine wound infection model

Background

The colonization of Staphylococcus aureus (SA) acquired in nosocomial infections may develop acute and chronic infections such as Methicillin-Resistant Staphylococcus aureus (MRSA) in the nose. As a commensal microorganism with the ability to form a biofilm, SA can dwell on the skin, nostrils, throat, perineum, and axillae of healthy humans. Nitric oxide (NO) is an unstable gas with various molecular functions and has antimicrobial properties which are converted into many potential treatments.

Methods

Methicillin-Resistant Staphylococcus aureus MRSA BAA1686 isolated from nasal infection was used in a porcine wound infection model. Deep partial-thickness wounds (10mm x 7mm x 0.5mm) were made on three animals using a specialized electrokeratome. All wounds were inoculated and then covered with polyurethane film dressings for biofilm formation. After 48 hours, three wounds were recovered from each animal for baseline enumeration. The remaining wounds were randomly assigned to six treatment groups and treated once daily. The treatment groups are as follows: NO topical ointments concentrations of 0.3, 0.9 and 1.8%, Vehicle Ointment, Mupirocin 2%, and Untreated Control. Microbiological recoveries were conducted on day 4 and day 7.

Results

The greatest efficacy observed from the NO formulations against MRSA BAA1686 was the 1.8% concentration. This agent was able to reduce more than 99% of bacterial counts when compared to Baseline, Vehicle Ointment, and Untreated Control wounds on both assessment days. Mupirocin 2% was the overall best treatment against MRSA BAA1686 on both assessment days, with a significant reduction (p ≤ 0.05) of 4.70 ± 0.13 Log CFU/mL from day 4 to day 7.

Conclusions

Overall, the positive control Mupirocin 2% was the most effective in eliminating MRSA BAA1686 throughout the study. This experiment demonstrated a downward trend from the highest concentration of NO topical ointment formulations to the lowest concentrations on both assessment days (0.3% - 1.8%). Out of all NO topical ointments, the highest concentration (1.8%) was the most effective with the potential to be an alternative treatment against a MRSA nasal strain biofilm.

Enhanced Nitric Oxide Delivery Through Self-Assembling Nanoparticles for Eradicating Gram-Negative Bacteria

In the current battle against antibiotic resistance, the resilience of Gram-negative bacteria against traditional antibiotics is due not only to their protective outer membranes but also to mechanisms like efflux pumps and enzymatic degradation of drugs, underscores the urgent need for innovative antimicrobial tactics. Herein, this study presents an innovative method involving the synthesis of three furoxan derivatives engineered to self-assemble into nitric oxide (NO) donor nanoparticles (FuNPs). These FuNPs, notably supplied together with polymyxin B (PMB), achieve markedly enhanced bactericidal efficacy against a wide spectrum of bacterial phenotypes at considerably lower NO concentrations (0.1-2.8 µg mL-1), which is at least ten times lower than the reported data for NO donors (≥200 µg mL-1). The bactericidal mechanism is elucidated using confocal, scanning, and transmission electron microscopy techniques. Neutron reflectometry confirms that FuNPs initiate membrane disruption by specifically engaging with the polysaccharides on bacterial surfaces, causing structural perturbations. Subsequently, PMB binds to lipid A on the outer membrane, enhancing permeability and resulting in a synergistic bactericidal action with FuNPs. This pioneering strategy underscores the utility of self-assembly in NO delivery as a groundbreaking paradigm to circumvent traditional antibiotic resistance barriers, marking a significant leap forward in the development of next-generation antimicrobial agents.

Antibacterial mechanism of CO2 combined with low temperature against Shewanella putrefaciens by biochemical and metabolomics analysis

To further reveal the inhibition mechanism of carbon dioxide (CO2) on Shewanella putrefaciens (S. putrefaciens), influence on metabolic function was studied by biochemical and metabolomics analysis. Accordingly, reduction of intracellular pH (pHi), depolarization of cell membrane and accumulation of reactive oxygen species (ROS) indicated that CO2 changed the membrane permeability of S. putrefaciens. Besides, adenosine triphosphate (ATP), ATPase, nicotinamide adenine dinucleotide (NAD+/NADH) and ratios of NADH/NAD+ were detected, indicating a role of CO2 in repressing respiratory pathway and electron transport. According to metabolomics results, CO2 induced differential expressions of metabolites, disordered respiratory chain and weakened energy metabolism of S. putrefaciens. Inhibition of respiratory rate-limiting enzymes also revealed that electron transfer of respiratory chain was blocked, cell respiration was weakened, and thus energy supply was insufficient under CO2 stress. These results revealed that CO2 caused disruption of metabolic function, which might be the main cause of growth inhibition for S. putrefaciens.

Nitric oxide-releasing self-healing hydrogel for antibacterial and antibiofilm efficacy against polymicrobial infection

Aim: Bacterial infections and the formation of biofilms are currently key factors in the delay of wound healing. S-Nitroso glutathione (GSNO) is recognized as a nitric oxide (NO) donor that exhibits potent antibacterial and antibiofilm activities. However, some of the stability limitations of NO require it to be prepared pharmaceutically.Materials & methods: Here, we developed a self-healing hydrogel dressing consisting of GSNO, polyvinyl alcohol/borax (PVA/B) and carboxymethyl chitosan (cmCHI). This research aimed to determine the antibacterial and antibiofilm activities of a self-healing hydrogel (PVA-B-cmCHI/GSNO) against multiple bacteria and polymicrobial biofilms.Results: Forty mg/ml PVA-B-cmCHI/GSNO significantly increased the antibacterial activity against Pseudomonas aeruginosa, S. aureus, Methicillin resistant Staphylococcus aureus (MRSA), as indicated by a >5 log reduction in bacterial viability (∼99.999% killing). PVA-B-cmCHI/GSNO showed antibiofilm activity three-times greater than that of the blank self-healing hydrogel (PVA-B-cmCHI) by inhibiting 80% of the biofilm formation.Conclusion: The results suggest that the NO-releasing self-healing hydrogels exhibit notable antibacterial and antibiofilm properties and thus could be a promising approach for the treatment of bacterial or biofilm-infected wounds.

Nanoparticle-Based Nitric Oxide Donors: Exploring Their Antimicrobial and Anti-Biofilm Capabilities

Background: Nitric oxide (NO) is an antimicrobial and anti-biofilm agent with significant potential for combating biofilm-associated infections and antibiotic resistance. However, owing to its high reactivity due to the possession of a free radical and short half-life (1-5 s), the practical application of NO in clinical settings is challenging. Objectives: This review explores the development of NO-releasing nanoparticles that provide a controlled, targeted delivery system for NO, enhancing its antimicrobial efficacy while minimizing toxicity. The review discusses various NO donors, nanoparticle platforms, and how NO disrupts biofilm formation and eradicates pathogens. Additionally, we examine the highly encouraging and inspiring results of NO-releasing nanoparticles against multidrug-resistant strains and their applications in medical and environmental contexts. This review highlights the promising role of NO-based nanotechnologies in overcoming the challenges posed by increasing antibiotic resistance and biofilm-associated infections. Conclusions: Although NO donors and nanoparticle delivery systems show great potential for antimicrobial and anti-biofilm uses, addressing challenges related to controlled release, toxicity, biofilm penetration, resistance, and clinical application is crucial.

Wearable nitric oxide-releasing antibacterial insert for preventing device-associated infections

Medical device-associated infections are a pervasive global healthcare concern, often leading to severe complications. Bacterial biofilms that form on indwelling medical devices, such as catheters, are significant contributors to infections like bloodstream and urinary tract infections. This study addresses the challenge of biofilms on medical devices by introducing a portable antimicrobial catheter insert (PACI) designed to be efficient, biocompatible, and anti-infective. The PACI utilizes nitric oxide (NO), known for its potent antimicrobial properties, to deter bacterial adhesion and biofilm formation. To achieve this, a photoinitiated NO donor, S-nitroso-N-acetylpenicillamine (SNAP), is covalently linked to a polydimethylsiloxane (PDMS) polymer. This design allows for higher NO loading for long-term impact and prevents premature donor leaching, a common challenge with SNAP-blended polymers. The SNAP-PDMS material was applied to a side-glowing fiber optic and connected to a wearable light module emitting 450 nm light, creating a functional antimicrobial insert. Activation of the fiber optic, accomplished with a one-click mechanism, enables real-time NO release, maintaining controlled NO levels for a minimum of 24  hours. The therapeutic levels of NO released via photocatalysis from the PACI demonstrated remarkable efficacy, with >90 % reduction in bacterial viability against S. aureus, S. epidermidis, and P. mirabilis without any cytotoxic impact on mammalian cells. This study underscores the potential of the NO-releasing insert in clinical settings, providing a portable and adaptable solution for preventing catheter-associated infections.

RABV antigenic peptide loaded polymeric nanoparticle production, characterization, and preliminary investigation of its biological activity

Nanoparticle-based antigen carrier systems have become a significant area of research with the advancement of nanotechnology. Biodegradable polymers have emerged as particularly promising carrier vehicles due to their ability to address the limitations of existing vaccine systems. In this study, we successfully encapsulated the G5-24 linear peptide, located between amino acids 253 and 275 in the primary sequence of the rabies virus G protein, into biodegradable and biocompatible PLGA copolymer using the double emulsion solvent evaporation method. The resulting nanoparticles had a size of approximately 230.9 ± 0.9074 nm, with a PDI value of 0.168 ± 0.017 and a zeta potential value of -9.86 ± 0.132 mV. SEM images confirmed that the synthesized nanoparticles were uniform in size and distribution. Additionally, FTIR spectra indicated successful peptide loading into the nanoparticles. The encapsulation efficiency of the peptide-loaded nanoparticles was 73.3%, with a peptide loading capacity of 48.2% and a reaction yield of 30.4%. Peptide release studies demonstrated that 65.55% of the peptide was released in a controlled manner over 28 d, following a 'biphasic burst release' profile consistent with the degradation profile of PLGA. This controlled release is particularly beneficial for vaccine studies. Cytotoxicity tests revealed that the R-NP formulation did not induce cytotoxicity in fibroblast cells and enhanced NO production in macrophages, indicating its potential for vaccine development.

Intraperitoneal Injection of the Porphyromonas gingivalis Outer Membrane Vesicle (OMV) Stimulated Expressions of Neuroinflammatory Markers and Histopathological Changes in the Brains of Adult Zebrafish

Porphyromonas gingivalis is the major pathogenic bacteria found in the subgingival plaque of patients with periodontitis, which leads to neuroinflammation. The bacteria destroy periodontal tissue through virulence factors, which are retained in the bacteria's outer membrane vesicles (OMV). This study aimed to determine the real-time effect of an intraperitoneal injection of P. gingivalis OMV on the production and expression of inflammatory markers and histopathological changes in adult zebrafishes' central nervous systems (CNS). Following the LD50 (21 µg of OMV), the zebrafish were injected intraperitoneally with 18 µg of OMVs, and the control group were injected with normal saline at seven different time points. Brains of experimental zebrafish were dissected at desired time points for colorimetric assays, ELISA, and histology. This study discovered that nitric oxide and PGE2 were significantly increased at 45 min, while IL-1β and IL-6 were expressed at subsequent 12 h and 24 h time points, respectively. Histopathological changes such as blood coagulation, astrocytosis, edema, spongiosis, and necrosis were observed between the 6hour and 24 h time points. The two apoptotic enzymes, caspases 3 and 9, were not expressed at any point. In summary, the OMV-induced neuroinflammatory responses and histopathological changes in adult zebrafish were time-point dependent. This study will enrich our understanding of the mechanism of P. gingivalis OMVs in neuroinflammation in a zebrafish model, most especially the timing of the expression of inflammatory mediators in relation to observable changes in brain tissues.

Eco-friendly film with highly efficient sterilization for food preservation by incorporating natural products into starch/polyvinyl alcohol matrix

An advanced biodegradable packaging film with antimicrobial and fresh-maintaining functions was constructed by incorporating berberine and L-arginine into the starch/polyvinyl alcohol (PVA) film matrix. The film was endowed with a dual antibacterial capacity thanks to the intrinsic antibacterial capability of berberine and cascaded photodynamic sterilization. The aggregated berberine presents an excellent photodynamic activity to generate reactive oxygen species (ROS), which further triggers the NO release from L-arginine. Under the synergetic action of ROS and NO, the as-prepared film not only has an antibacterial efficiency of over 99 % against both S. aureus and E. coli but also delays fruit ripening through antagonistic effects on ethylene to extend the shelf life of food. Meanwhile, the as-prepared film presents UV-shielding properties, thermal stability, and considerable mechanical properties. Specifically, the packaging film exhibits good biocompatibility and is biodegradable, with a degradation rate of 56 % within 16 days, which has great potential for improving food safety and environmental events.

The progress and future of the treatment of Candida albicans infections based on nanotechnology

Systemic infection with Candida albicans poses a significant risk for people with weakened immune systems and carries a mortality rate of up to 60%. However, current therapeutic options have several limitations, including increasing drug tolerance, notable off-target effects, and severe adverse reactions. Over the past four decades, the progress in developing drugs to treat Candida albicans infections has been sluggish. This comprehensive review addresses the limitations of existing drugs and summarizes the efforts made toward redesigning and innovating existing or novel drugs through nanotechnology. The discussion explores the potential applications of nanomedicine in Candida albicans infections from four perspectives: nano-preparations for anti-biofilm therapy, innovative formulations of "old drugs" targeting the cell membrane and cell wall, reverse drug resistance therapy targeting subcellular organelles, and virulence deprivation therapy leveraging the unique polymorphism of Candida albicans. These therapeutic approaches are promising to address the above challenges and enhance the efficiency of drug development for Candida albicans infections. By harnessing nano-preparation technology to transform existing and preclinical drugs, novel therapeutic targets will be uncovered, providing effective solutions and broader horizons to improve patient survival rates.

Engineering a Novel Probiotic Toolkit in Escherichia coli Nissle 1917 for Sensing and Mitigating Gut Inflammatory Diseases

Inflammatory bowel disease (IBD) is characterized by chronic intestinal inflammation with no cure and limited treatment options that often have systemic side effects. In this study, we developed a target-specific system to potentially treat IBD by engineering the probiotic bacterium Escherichia coli Nissle 1917 (EcN). Our modular system comprises three components: a transcription factor-based sensor (NorR) capable of detecting the inflammation biomarker nitric oxide (NO), a type 1 hemolysin secretion system, and a therapeutic cargo consisting of a library of humanized anti-TNFα nanobodies. Despite a reduction in sensitivity, our system demonstrated a concentration-dependent response to NO, successfully secreting functional nanobodies with binding affinities comparable to the commonly used drug Adalimumab, as confirmed by enzyme-linked immunosorbent assay and in vitro assays. This newly validated nanobody library expands EcN therapeutic capabilities. The adopted secretion system, also characterized for the first time in EcN, can be further adapted as a platform for screening and purifying proteins of interest. Additionally, we provided a mathematical framework to assess critical parameters in engineering probiotic systems, including the production and diffusion of relevant molecules, bacterial colonization rates, and particle interactions. This integrated approach expands the synthetic biology toolbox for EcN-based therapies, providing novel parts, circuits, and a model for tunable responses at inflammatory hotspots.

Multi-component liquid-infused systems: a new approach to functional coatings

Antifouling liquid-infused surfaces have generated interest in multiple fields due to their diverse applications in industry and medicine. In nearly all reports to date, the liquid component consists of only one chemical species. However, unlike traditional solid surfaces, the unique nature of liquid surfaces holds the potential for synergistic and even adaptive functionality simply by including additional elements in the liquid coating. In this work, we explore the concept of multi-component liquid-infused systems, in which the coating liquid consists of a primary liquid and a secondary component or components that provide additional functionality. For ease of understanding, we categorize recently reported multi-component liquid-infused surfaces according to the size of the secondary components: molecular scale, in which the secondary components are molecules; nanoscale, in which they are nanoparticles or their equivalent; and microscale, in which the additional components are micrometer size or above. We present examples at each scale, showing how introducing a secondary element into the liquid can result in synergistic effects, such as maintaining a pristine surface while actively modifying the surrounding environment, which are difficult to achieve in other surface treatments. The review highlights the diversity of fabrication methods and provides perspectives on future research directions. Introducing secondary components into the liquid matrix of liquid-infused surfaces is a promising strategy with significant potential to create a new class of multifunctional materials. Keywords: Active surfaces; Antimicrobial; Antifouling; Interfaces; Sensing surfaces.

Simultaneous photoactivation of a fluoroquinolone antibiotic and nitric oxide with fluorescence reporting

The achievement of smart pharmaceuticals whose bioactivity can be spatiotemporally controlled by light stimuli is known as photopharmacology, an emerging area aimed at improving the therapeutic outcome and minimizing side effects. This is especially attractive for antibiotics, for which the inevitable development of multidrug resistance and the dwindling of new clinically approved drugs represent the main drawbacks. Here, we show that nitrosation of the fluoroquinolone norfloxacin (NF), a broad-spectrum antibiotic, leads to the nitrosated bioconjugate NF-NO, which is inactive at the typical minimum inhibitory concentration of NF. Irradiation of NF-NO with visible blue light triggers the simultaneous release of NF and nitric oxide (NO). The photouncaging process is accompanied by the revival of the typical fluorescence emission of NF, quenched in NF-NO, which acts as an optical reporter. This permits the real-time monitoring of the photouncaging process, even within bacteria cells where antibacterial activity is switched on exclusively upon light irradiation. The mechanism of photorelease seems to occur through a two-step hopping electron transfer mediated by the lowest triplet state of NF-NO and the phosphate buffer ions or aminoacids such as tyrosine. Considering the well-known role of NO as an "unconventional" antibacterial, the NF-NO conjugate may represent a potential bimodal antibacterial weapon activatable on demand with high spatio-temporal control.

Weathered polyethylene microplastics induced immunomodulation in zebrafish

Microplastics are pollutants of emerging concern and the aquatic biota consumes microplastics (MPs), which has a range of toxicological and environmental effects on aquatic organisms that are not the intended targets. The current study looked into how weathered polyethylene (wPE) MPs affected Danio albolineatus immunological and haematological markers. In this experiment, fish of both sexes were placed in control and exposure groups, and they were exposed for 40 d at the sublethal level (1 μg L-1) of fragmented wPE, which contained 1074 ± 52 MPs per litre. Similarly, fish exposed to wPE MPs showed significant modifications in lysozyme, antimicrobial, and antiprotease activity, as well as differential counts. Results of the present study show that the male fish were more susceptible than female fish after 40 d of chronic exposure. Further studies are needed to ascertain how the innate and humoral immune systems of the fish respond to MPs exposure.

Implications of ammonia stress for the pathogenicity of Shewanella spp. in Oreochromis niloticus: effects on hematological, biochemical, immunological, and histopathological parameters

Environmental stressors (such as ammonia) in aquaculture could increase the risk of pathogenicity, posing a more severe threat to farmed fish. The aim of this study was to investigate the effects of ammonia stress on the pathogenicity of Shewanella spp. in Oreochromis niloticus. First, a 96-hour static test was used to determine the median lethal concentration (LC50) of unionized ammonia to Nile tilapia. After 96 h of exposure, the Un-ionized ammonia (UIA) LC50 was estimated to be 4.26 mg/L. Second, an experiment was conducted to test the effect of unionized ammonia stress on the pathogenicity of Shewanella spp. in O. niloticus for 30 days. A study involved 180 fish divided into six groups, with the first group serving as a control. The second group (AMN1/10) and the third group (AMN1/20) were not challenged and were exposed to 1/10 (0.42 mg/L) and 1/20 (0.21 mg/L) of the 96-hour LC50 of UIA, respectively. Then 0.2 mL (0.14 × 105) of Shewanella spp. was intraperitoneally injected into the fourth (SH), fifth (SH + AMN1/10), and sixth (SH + AMN1/20) groups, which were subjected to 0, 1/10 (0.42 mg/L), and 1/20 (0.21 mg/L) of the 96-hour LC50 of UIA, respectively. The survival rate, hematological indices, immunological parameters, and antioxidant activity of the fish significantly decreased when they were exposed to ammonia and Shewanella infection separately or together. Histopathological changes were also observed in the kidney and liver. Furthermore, both individual and combined exposures significantly altered renal and hepatic function, with notable increases in glucose and cortisol levels, as well as in the expression of proinflammatory cytokine genes (TNF-α and IL-1ß). However, the detrimental effects of co-exposure to ammonia stress and Shewanella infection were greater than those of separate exposures. As a result, we may say that increased ammonia concentrations enhance the infection of Shewanella spp. These findings could contribute to a better understanding of Shewanella infection in Nile tilapia.

Insights into Chlamydia Development and Host Cells Response

Chlamydia infections commonly afflict both humans and animals, resulting in significant morbidity and imposing a substantial socioeconomic burden worldwide. As an obligate intracellular pathogen, Chlamydia interacts with other cell organelles to obtain necessary nutrients and establishes an intracellular niche for the development of a biphasic intracellular cycle. Eventually, the host cells undergo lysis or extrusion, releasing infectious elementary bodies and facilitating the spread of infection. This review provides insights into Chlamydia development and host cell responses, summarizing the latest research on the biphasic developmental cycle, nutrient acquisition, intracellular metabolism, host cell fates following Chlamydia invasion, prevalent diseases associated with Chlamydia infection, treatment options, and vaccine prevention strategies. A comprehensive understanding of these mechanisms will contribute to a deeper comprehension of the intricate equilibrium between Chlamydia within host cells and the progression of human disease.

Antimicrobial properties of hindered amine light stabilizers in polymer coating materials and their mechanism of action

UV-stabilizers are a class of additives that provide extended polymer resistance to UV-degradation, but have also been suggested to have antimicrobial activity, potentially preventing the spread of pathogens, and inhibiting microbial-induced biodegradation. In this work, we incorporated different UV-stabilizers, a hindered amine light stabilizer (HALS), Tinuvin 770 DF and Tinuvin PA 123, or a hybrid HALS/UV-absorber, Tinuvin 5151, in polyurethane formulations to produce lacquer-films, and tested their antimicrobial activity against Staphylococcus aureus (methicillin-resistant and -sensitive strains), Escherichia coli and Candida albicans. Lacquer-films incorporated with Tinuvin 770 DF showed strong antimicrobial performance against bacteria and fungi, while maintaining cytocompatibility. The mechanism of action revealed a positive relationship between Tinuvin 770 DF concentration, microbial death, and reactive nitrogen species (RNS), suggesting that RNS produced during autoxidation of Tinuvin 770 DF is responsible for the antimicrobial properties of this UV-stabilizer. Conversely, lacquer-films incorporated with Tinuvin 5151 or Tinuvin PA 123 exhibited no antimicrobial properties. Collectively, these results highlight the commercial potential of Tinuvin 770 DF to prevent photo- and biodegradation of polymers, while also inhibiting the spread of potentially harmful pathogens. Furthermore, we provide a better understanding of the mechanism underlying the biocidal activity of HALS associated to autooxidation of the amine group.

Fabrication and Optimization of Poly(ε-caprolactone) Microspheres Loaded with S-Nitroso-N-Acetylpenicillamine for Nitric Oxide Delivery

Heart disease is one of the leading causes of death in the United States and throughout the world. While there are different techniques for reducing or preventing the impact of heart disease, nitric oxide (NO) is administered as nitroglycerin for reversing angina or chest pain. Unfortunately, due to its gaseous and short-lived half-life, NO can be difficult to study or even administer. Therefore, controlled delivery of NO is desirable for therapeutic use. In the current study, the goal was to fabricate NO-releasing microspheres (MSs) using a donor molecule, S-Nitroso-N-Acetyl penicillamine, (SNAP), and encapsulating it in poly(ε-caprolactone) (PCL) using a single-emulsion technique that can provide sustained delivery of NO to cells over time without posing any toxicity risks. Optimization of the fabrication process was performed by varying the duration of homogenization (5, 10, and 20 min) and its effect on entrapment efficiency and size. The optimized SNAP-MS had an entrapment efficiency of ˃50%. Furthermore, we developed a modified method for NO detection by using NO microsensors to detect the NO release from SNAP-MSs in real time, showing sustained release behavior. The fabricated SNAP-MSs were tested for biocompatibility with HUVECs (human umbilical vein endothelial cells), which were found to be biocompatible. Lastly, we tested the effect of controlled NO delivery to human induced pluripotent stem-derived cardiomyocytes (hiPSC-CMs) via SNAP-MSs, which showed a significant improvement in the electrophysiological parameters and alleviated anoxic stress.

Stepwise Nitric Oxide Release and Antibacterial Activity of a Nitric Oxide Photodonor Hosted within Cyclodextrin Branched Polymer Nanocarriers

A hydrophobic nitric oxide (NO) photodonor integrating both nitroso and nitro functionalities within its chromophoric skeleton has been synthesized. Excitation of this compound with blue light triggers the release of two NO molecules from the nitroso and the nitro functionalities via a stepwise mechanism. Encapsulation of the NO photodonor within biocompatible neutral, cationic, and anionic β-cyclodextrin branched polymers as suitable carriers leads to supramolecular nanoassemblies, which exhibit the same nature of the photochemical processes but NO photorelease performances enhanced by about 1 order of magnitude when compared with the free guest. Antibacterial tests carried out with methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii demonstrate an effective antibacterial activity exclusively under light activation and point out a differentiated role of the polymeric nanocarriers in determining the outcome of the antibacterial photodynamic action.

Metalloproteins structural and functional insights into immunological patterns

Metalloproteins play a crucial role in regulating different aspects of the immune system in humans. They have various functions in immunity, including recognizing and presenting antigens, aiding in the movement and effectiveness of immune cells, and facilitating interactions between the host and pathogens. Understanding how these proteins work can help us develop new methods to control the immune response in different diseases. Metalloproteins contain metal ions in their structure, which allows them to perform these diverse functions. They encompass a wide range of enzymes, signaling molecules, and structural proteins that utilize metal ions as cofactors for their activities. Examples of metalloproteins include superoxide dismutase, catalase, and metalloproteases, which regulate oxidative stress, inflammation, and tissue remodelling processes associated with immune activation. By studying their functions and the effects of their dysfunction, researchers can develop strategies to improve immune function and combat various diseases. This review explores the diverse functions of metalloproteins in immune processes, highlighting their significance in both health and disease.

Synergistic photogeneration of nitric oxide and singlet oxygen by nanofiber membranes via blue and/or red-light irradiation: Strong antibacterial action

New functionalities were added to biocompatible polycaprolactone nanofiber materials through the co-encapsulation of chlorin e6 trimethyl ester (Ce6) photogenerating singlet oxygen and absorbing light both in the blue and red regions, and using 4-(N-(aminopropyl)-3-(trifluoromethyl)-4-nitrobenzenamine)-7-nitrobenzofurazan, NO-photodonor (NOP), absorbing light in the blue region of visible light. Time-resolved and steady-state luminescence, as well as absorption spectroscopy, were used to monitor both photoactive compounds. The nanofiber material exhibited photogeneration of antibacterial species, specifically nitric oxide and singlet oxygen, upon visible light excitation. This process resulted in the efficient photodynamic inactivation of E. coli not only close to nanofiber material surfaces due to short-lived singlet oxygen, but even at longer distances due to diffusion of longer-lived nitric oxide. Interestingly, nitric oxide was also formed by processes involving photosensitization of Ce6 during irradiation by red light. This is promising for numerous applications, especially in the biomedical field, where strictly local photogeneration of NO and its therapeutic benefits can be applied using excitation in the "human body phototherapeutic window" (600-850 nm). Generally, due to the high permeability of red light, the photogeneration of NO can be achieved in any aqueous environment where direct excitation of NOP to its absorbance in the blue region is limited.

A hyaluronic acid hydrogel as a mild photothermal antibacterial, antioxidant, and nitric oxide release platform for diabetic wound healing

Hyaluronic acid (HA)-based biopolymer hydrogels are promising therapeutic dressings for various wounds but still underperform in treating diabetic wounds. These wounds are extremely difficult to heal and undergo a prolonged and severe inflammatory process due to bacterial infection, overexpression of reactive oxygen species (ROS), and insufficient synthesis of NO. In this study, a dynamic crosslinked hyaluronic acid (HA) hydrogel dressing (Gel-HAB) loaded with allomelanin (AMNP)-N, N'-dis-sec-butyl-N, N'-dinitroso-1, 4-phenylenediamine (BNN6) nanoparticles (AMNP-BNN6) was developed for healing diabetic wounds. The dynamic acylhydrazone bond formed between hydrazide-modified HA (HA-ADH) and oxidized HA (OHA) makes the hydrogel injectable, self-healing, and biocompatible. The hydrogel, loaded with AMNP-BNN6 nanoparticles, exhibits promising ROS scavenging ability and on-demand release of nitric oxide (NO) under near-infrared (NIR) laser irradiation to achieve mild photothermal antibacterial therapy (PTAT) (∼ 48 °C). Notably, the Gel-HAB hydrogel effectively reduced the oxidative stress level, controlled infections, accelerated vascular regeneration, and promoted angiogenesis, thereby achieving rapid healing of diabetic wounds. The injectable self-healing nanocomposite hydrogel could serve as a mild photothermal-enhanced antibacterial, antioxidant, and nitric oxide release platform for the treatment of diabetic wounds.

Bioenergetics of simultaneous oxygen and nitrate respiration and nitric oxide production in a Pseudomonas aeruginosa agar colony biofilm

Pseudomonas aeruginosa is a biofilm forming pathogen commonly associated with infection of the cystic fibrosis (CF) lung, chronic wounds and indwelling medical devices. P. aeruginosa is a facultative aerobe that can use nitrate (NO3-) found in healthy and infected tissues and body fluids to generate energy through denitrification. Further, P. aeruginosa the expression of denitrification genes has been found in specimens from people with CF. The main aim of this study was to determine the relative energy contribution of oxygen (O2) respiration and denitrification in single Pseudomonas aeruginosa PAO1 biofilm colonies under different O2 concentrations to estimate the possible relative importance of these metabolic processes in the context of biofilm infections. We showed that the used strain PAO1 in biofilms denitrified with nitrous oxide (N2O), and not nitrogen (N2), as the end product in our incubations. From simultaneous O2 and N2O microprofiles measured with high spatial resolution by microsensors in agar colony biofilms under air, N2 and pure O2, the rates of aerobic respiration and denitrification were calculated and converted to ATP production rates. Denitrification occurred both in the oxic and anoxic zones, and became increasingly dominant with decreasing O2 concentrations. At O2 concentrations characteristic for tissues and wounds (20-60 μM), denitrification was responsible for 50% of the total energy conservation in the biofilm. In addition the formation of nitric oxide (NO), a precursor of N2O and an important regulator of many cellular processes, was strongly influenced by the local O2 concentrations. NO production was inhibited under pure O2, present under anoxia (∼1 μM) and remarkably high (up to 6 μM) under intermediate O2 levels, which can be found in infected tissues. Possible impacts of such NO levels on both the host and the biofilm bacteria are discussed.

Preventing Staphylococci Surgical Site Infections with a Nitric Oxide-Releasing Poly(lactic acid-co-glycolic acid) Suture Material

Of the 27 million surgeries performed in the United States each year, a reported 2.6% result in a surgical site infection (SSI), and Staphylococci species are commonly the culprit. Alternative therapies, such as nitric oxide (NO)-releasing biomaterials, are being developed to address this issue. NO is a potent antimicrobial agent with several modes of action, including oxidative and nitrosative damage, disruption of bacterial membranes, and dispersion of biofilms. For targeted antibacterial effects, NO is delivered by exogenous donor molecules, like S-nitroso-N-acetylpenicillamine (SNAP). Herein, the impregnation of SNAP into poly(lactic-co-glycolic acid) (PLGA) for SSI prevention is reported for the first time. The NO-releasing PLGA copolymer is fabricated and characterized by donor molecule loading, leaching, and the amount remaining after ethylene oxide sterilization. The swelling ratio, water uptake, static water contact angle, and tensile strength are also investigated. Furthermore, its cytocompatibility is tested against 3T3 mouse fibroblast cells, and its antimicrobial efficacy is assessed against multiple Staphylococci strains. Overall, the NO-releasing PLGA copolymer holds promise as a suture material for eradicating surgical site infections caused by Staphylococci strains. SNAP impregnation affords robust antibacterial properties while maintaining the cytocompatibility and mechanical integrity.

Applications of nitric oxide-releasing nanomaterials in dermatology: Skin infections and wound healing

Nitric oxide (NO) is produced in most cells in the skin and is an important regulator of essential cutaneous functions, including responses to UV irradiation, microbial defense, wound healing, melanogenesis and epidermal permeability barrier homeostasis. Harnessing the physiological activities of NO for therapeutic use is difficult because the molecule is highly reactive and unstable. A variety of exogenous NO delivery platforms have been developed and evaluated; however, they have limited clinical applications in dermatology due to instability and poor cutaneous penetration. NO-releasing nanomaterials overcome these limitations, providing targeted tissue delivery, and sustained and controlled NO release. This review provides a comprehensive and up-to-date evaluation of the use of NO-releasing nanomaterials in dermatology for the treatment of skin and soft tissue infections and wound healing.

Blends of Organic Acids Are Weaponizing the Host iNOS and Nitric Oxide to Reduce Infection of Piscirickettsia salmonis in vitro

For the last 30 years, Piscirickettsia salmonis has caused major economic losses to the aquaculture industry as the aetiological agent for the piscirickettsiosis disease. Replacing the current interventions, based on antibiotics, with natural alternatives (e.g., organic acids) represents a priority. With this study, we aimed to better understand their biological mechanism of action in an in vitro model of infection with salmon epithelial cells (CHSE-214). Our first observation revealed that at the sub-inhibitory concentration of 0.5%, the organic acid blend (Aq) protected epithelial cell integrity and significantly reduced P. salmonis invasion. The MIC was established at 1% Aq and the MBC at 2% against P. salmonis. The sub-inhibitory concentration significantly increased the expression of the antimicrobial peptides Cath2 and Hepcidin1, and stimulated the activity of the innate immune effector iNOS. The increase in iNOS activity also led to higher levels of nitric oxide (NO) being released in the extracellular space. The exposure of P. salmonis to the endogenous NO caused an increase in bacterial lipid peroxidation levels, a damaging effect which can ultimately reduce the pathogen's ability to attach or multiply intracellularly. We also demonstrate that the increased NO release by the host CHSE-214 cells is a consequence of direct exposure to Aq and is not dependent on P. salmonis infection. Additionally, the presence of Aq during P. salmonis infection of CHSE-214 cells significantly mitigated the expression of the pro-inflammatory cytokines IL-1β, IL-8, IL-12, and IFNγ. Taken together, these results indicate that, unlike antibiotics, natural antimicrobials can weaponize the iNOS pathway and secreted nitric oxide to reduce infection and inflammation in a Piscirickettsia salmonis in vitro model of infection.

Dual-Targeted Graphitic Cascade Nanozymes for Recognition and Treatment of Helicobacter pylori

Helicobacter pylori (H. pylori) is the major etiological factor of a variety of gastric diseases. However, the treatment of H. pylori is challenged by the destruction of targeted drugs by gastric acid and pepsin. Herein, a dual-targeted cascade catalytic nanozyme PtCo@Graphene@Hemin-2(L-arginine) (PtCo@G@H2A) is designed for the treatment of H. pylori. The dual-targeting ability of PtCo@G@H2A is derived from directly targeting the receptor protein of H. pylori through hemin and responding to the acidic environment to cause charge reversal (protonation of L-arginine) to capture H. pylori, achieving efficient targeting effect. Compared with the single-targeting strategy relying on hemin, the dual-targeting strategy can greatly improve the targeting rate, achieving an increase of 850% targeting rate. At the concentration of NaHCO3 in intestinal fluid, the surface potential of PtCo@G@H2A can be quickly restored to avoid side effects. Meanwhile, PtCo@G@H2A has pH-responsive oxidase-like activity, which can generate nitric oxide (NO) through a cascade catalytic process that first generates reactive oxygen species (ROS) with oxygen, and further oxidizes L-arginine through ROS, realizing a superior acid-selective bactericidal effect. Overall, it proposes a promising strategy for the treatment of H. pylori that maintains high targeting and therapeutic effects in the environment of gastric acid and pepsin.