Intravenous anti-MRSA phosphatiosomes mediate enhanced affinity to pulmonary surfactants for effective treatment of infectious pneumonia

Strategies to Promote the Journey of Nanoparticles Against Biofilm-Associated Infections

Biofilm-associated infections are one of the most challenging healthcare threats for humans, accounting for 80% of bacterial infections, leading to persistent and chronic infections. The conventional antibiotics still face their dilemma of poor therapeutic effects due to the high tolerance and resistance led by bacterial biofilm barriers. Nanotechnology-based antimicrobials, nanoparticles (NPs), are paid attention extensively and considered as promising alternative. This review focuses on the whole journey of NPs against biofilm-associated infections, and to clarify it clearly, the journey is divided into four processes in sequence as 1) Targeting biofilms, 2) Penetrating biofilm barrier, 3) Attaching to bacterial cells, and 4) Translocating through bacterial cell envelope. Through outlining the compositions and properties of biofilms and bacteria cells, recent advances and present the strategies of each process are comprehensively discussed to combat biofilm-associated infections, as well as the combined strategies against these infections with drug resistance, aiming to guide the rational design and facilitate wide application of NPs in biofilm-associated infections.

Neutrophil-targeted combinatorial nanosystems for suppressing bacteremia-associated hyperinflammation and MRSA infection to improve survival rates

There is currently no specific and effective treatment for bacteremia-mediated sepsis. Hence, this study engineered a combinatorial nanosystem containing neutrophil-targeted roflumilast-loaded nanocarriers and non-targeted fusidic acid-loaded nanoparticles to enable the dual mitigation of bacteremia-associated inflammation and methicillin-resistant Staphylococcus aureus (MRSA) infection. The targeted nanoparticles were developed by conjugating anti-lymphocyte antigen 6 complex locus G6D (Ly6G) antibody fragment on the nanoparticulate surface. The particle size and zeta potential of the as-prepared nanosystem were about 200 nm and -25 mV, respectively. The antibody-conjugated nanoparticles showed a three-fold increase in neutrophil internalization compared to the unfunctionalized nanoparticles. As a selective phosphodiesterase (PDE) 4 inhibitor, the roflumilast in the nanocarriers largely inhibited cytokine/chemokine release from the activated neutrophils. The fusidic acid-loaded nanocarriers were vital to eliminate biofilm MRSA colony by 3 log units. The nanoparticles drastically decreased the intracellular bacterial count compared to the free antibiotic. The in vivo mouse bioimaging demonstrated prolonged retention of the nanosystem in the circulation with limited organ distribution and liver metabolism. In the mouse bacteremia model, the multifunctional nanosystem produced a 1‒2 log reduction of MRSA burden in peripheral organs and blood. The functionalized nanosystem arrested the cytokine/chemokine overexpression greater than the unfunctionalized nanocarriers and free drugs. The combinatory nanosystem also extended the median survival time from 50 to 103 h. No toxicity from the nanoformulation was found based on histology and serum biochemistry. Furthermore, our data proved that the active neutrophil targeting by the versatile nanosystem efficiently alleviated MRSA infection and organ dysfunction caused by bacteremia. STATEMENT OF SIGNIFICANCE: Bacteremia-mediated sepsis poses a significant challenge in clinical practice, as there is currently no specific and effective treatment available. In our study, we have developed a novel combinatorial nanosystem to address this issue. Our nanosystem consists of neutrophil-targeted roflumilast-loaded nanocarriers and non-targeted fusidic acid-loaded nanoparticles, enabling the simultaneous mitigation of bacteremia-associated inflammation and MRSA infection. Our nanosystem demonstrated the decreased neutrophil activation, effective inhibition of cytokine release, elimination of MRSA biofilm colonies, and reduced intracellular bacterial counts. In vivo experiments showed prolonged circulation, limited organ distribution, and increased survival rates in a mouse bacteremia model. Importantly, our nanosystem exhibited no toxicity based on comprehensive assessments.

Advancing biofilm management through nanoformulation strategies: a review of dosage forms and administration routes

Biofilms are complex microbial communities formed by the attachment of bacteria or fungi to surfaces encased in a self-produced polymeric matrix. These biofilms are highly resistant to conventional antimicrobial therapies. The resistance mechanisms exhibited by biofilms include low antibiotic absorption, sluggish replication, adaptive stress response, and the formation of dormant-like phenotypes. The eradication of biofilms requires alternative strategies and approaches. Nanotechnological drug delivery systems allow excellent control over the drug chemistry, surface area, particle size, particle shape, and composition of nanostructures. Nanoformulations can enhance the efficacy of antimicrobial agents by improving their bioavailability, stability, and targeted delivery to the site of infection that helps biofilm eradication more effectively. In addition to nanoformulations, the route of administration and choice of dosage forms play a crucial role in treating biofilm infections. Systemic administration of antibiotics is effective in controlling systemic infection and sepsis associated with biofilms. Alternative routes of administration, such as inhalation, vaginal, ocular, or dermal, have been explored to target biofilm infections in specific organs. This review primarily examines the utilisation of nanoformulations in various administration routes for biofilm management. It also provides an overview of biofilms, current approaches, and the drawbacks associated with conventional methods.

Nanomedicine: New Frontiers in Fighting Microbial Infections

Microbes have dominated life on Earth for the past two billion years, despite facing a variety of obstacles. In the 20th century, antibiotics and immunizations brought about these changes. Since then, microorganisms have acquired resistance, and various infectious diseases have been able to avoid being treated with traditionally developed vaccines. Antibiotic resistance and pathogenicity have surpassed antibiotic discovery in terms of importance over the course of the past few decades. These shifts have resulted in tremendous economic and health repercussions across the board for all socioeconomic levels; thus, we require ground-breaking innovations to effectively manage microbial infections and to provide long-term solutions. The pharmaceutical and biotechnology sectors have been radically altered as a result of nanomedicine, and this trend is now spreading to the antibacterial research community. Here, we examine the role that nanomedicine plays in the prevention of microbial infections, including topics such as diagnosis, antimicrobial therapy, pharmaceutical administration, and immunizations, as well as the opportunities and challenges that lie ahead.

Regulation of Staphylococcus aureus Virulence and Application of Nanotherapeutics to Eradicate S. aureus Infection

Staphylococcus aureus is a versatile pathogen known to cause hospital- and community-acquired, foodborne, and zoonotic infections. The clinical infections by S. aureus cause an increase in morbidity and mortality rates and treatment costs, aggravated by the emergence of drug-resistant strains. As a multi-faceted pathogen, it is imperative to consolidate the knowledge on its pathogenesis, including the mechanisms of virulence regulation, development of antimicrobial resistance, and biofilm formation, to make it amenable to different treatment strategies. Nanomaterials provide a suitable platform to address this challenge, with the potential to control intracellular parasitism and multidrug resistance where conventional therapies show limited efficacy. In a nutshell, the first part of this review focuses on the impact of S. aureus on human health and the role of virulence factors and biofilms during pathogenesis. The second part discusses the large diversity of nanoparticles and their applications in controlling S. aureus infections, including combination with antibiotics and phytochemicals and the incorporation of antimicrobial coatings for biomaterials. Finally, the limitations and prospects using nanomaterials are highlighted, aiming to foster the development of novel nanotechnology-driven therapies against multidrug-resistant S. aureus.

Nanomaterials for Delivering Antibiotics in the Therapy of Pneumonia

Bacterial pneumonia is one of the leading causes of death worldwide and exerts a significant burden on health-care resources. Antibiotics have long been used as first-line drugs for the treatment of bacterial pneumonia. However, antibiotic therapy and traditional antibiotic delivery are associated with important challenges, including drug resistance, low bioavailability, and adverse side effects; the existence of physiological barriers further hampers treatment. Fortunately, these limitations may be overcome by the application of nanotechnology, which can facilitate drug delivery while improving drug stability and bioavailability. This review summarizes the challenges facing the treatment of bacterial pneumonia and also highlights the types of nanoparticles that can be used for antibiotic delivery. This review places a special focus on the state-of-the-art in nanomaterial-based approaches to the delivery of antibiotics for the treatment of pneumonia.

Advances in Nanostructures for Antimicrobial Therapy

Microbial infections caused by a variety of drug-resistant microorganisms are more common, but there are fewer and fewer approved new antimicrobial chemotherapeutics for systemic administration capable of acting against these resistant infectious pathogens. Formulation innovations of existing drugs are gaining prominence, while the application of nanotechnologies is a useful alternative for improving/increasing the effect of existing antimicrobial drugs. Nanomaterials represent one of the possible strategies to address this unfortunate situation. This review aims to summarize the most current results of nanoformulations of antibiotics and antibacterial active nanomaterials. Nanoformulations of antimicrobial peptides, synergistic combinations of antimicrobial-active agents with nitric oxide donors or combinations of small organic molecules or polymers with metals, metal oxides or metalloids are discussed as well. The mechanisms of actions of selected nanoformulations, including systems with magnetic, photothermal or photodynamic effects, are briefly described.

Meta-Analysis of Drug Delivery Approaches for Treating Intracellular Infections

This meta-analysis aims to evaluate the trend, methodological quality and completeness of studies on intracellular delivery of antimicrobial agents. PubMed, Embase, and reference lists of related reviews were searched to identify original articles that evaluated carrier-mediated intracellular delivery and pharmacodynamics (PD) of antimicrobial therapeutics against intracellular pathogens in vitro and/or in vivo. A total of 99 studies were included in the analysis. The most commonly targeted intracellular pathogens were bacteria (62.6%), followed by viruses (16.2%) and parasites (15.2%). Twenty-one out of 99 (21.2%) studies performed neither microscopic imaging nor flow cytometric analysis to verify that the carrier particles are present in the infected cells. Only 31.3% of studies provided comparative inhibitory concentrations against a free drug control. Approximately 8% of studies, albeit claimed for intracellular delivery of antimicrobial therapeutics, did not provide any experimental data such as microscopic imaging, flow cytometry, and in vitro PD. Future research on intracellular delivery of antimicrobial agents needs to improve the methodological quality and completeness of supporting data in order to facilitate clinical translation of intracellular delivery platforms for antimicrobial therapeutics.

Different Nanotechnology Approaches for Ciprofloxacin Delivery Against Multidrug-Resistant Microbes

The percentages of organisms exhibiting antimicrobial resistance, especially resistance to multiple antibiotics, are incessantly increasing. Studies investigated that many bacteria are being resistant to ciprofloxacin. This review addresses the current knowledge on nano-based ciprofloxacin delivery approaches to improve its effectiveness and overcome the resistance issues. Ciprofloxacin delivery can be modified by encapsulating with or incorporating in different polymeric nanoparticles such as chitosan, PLGA, albumin, arginine, and other organic and inorganic nanostructure systems. Most of these nano-approaches are promising as an alternative strategy to improve the therapeutic effectiveness of ciprofloxacin in the future.

Inflammation-modulating nanoparticles for pneumonia therapy

Pneumonia is a common but serious infectious disease, and is the sixth leading cause for death. The foreign pathogens such as viruses, fungi, and bacteria establish an inflammation response after interaction with lung, leading to the filling of bronchioles and alveoli with fluids. Although the pharmacotherapies have shown their great effectiveness to combat pathogens, advanced methods are under developing to treat complicated cases such as virus-infection and lung inflammation or acute lung injury (ALI). The inflammation modulation nanoparticles (NPs) can effectively suppress immune cells and inhibit inflammatory molecules in the lung site, and thereby alleviate pneumonia and ALI. In this review, the pathological inflammatory microenvironments in pneumonia, which are instructive for the design of biomaterials therapy, are summarized. The focus is then paid to the inflammation-modulating NPs that modulate the inflammatory cells, cytokines and chemokines, and microenvironments of pneumonia for better therapeutic effects. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Respiratory Disease.

Nanomedicine for acute respiratory distress syndrome: The latest application, targeting strategy, and rational design

Acute respiratory distress syndrome (ARDS) is characterized by the severe inflammation and destruction of the lung air-blood barrier, leading to irreversible and substantial respiratory function damage. Patients with coronavirus disease 2019 (COVID-19) have been encountered with a high risk of ARDS, underscoring the urgency for exploiting effective therapy. However, proper medications for ARDS are still lacking due to poor pharmacokinetics, non-specific side effects, inability to surmount pulmonary barrier, and inadequate management of heterogeneity. The increased lung permeability in the pathological environment of ARDS may contribute to nanoparticle-mediated passive targeting delivery. Nanomedicine has demonstrated unique advantages in solving the dilemma of ARDS drug therapy, which can address the shortcomings and limitations of traditional anti-inflammatory or antioxidant drug treatment. Through passive, active, or physicochemical targeting, nanocarriers can interact with lung epithelium/endothelium and inflammatory cells to reverse abnormal changes and restore homeostasis of the pulmonary environment, thereby showing good therapeutic activity and reduced toxicity. This article reviews the latest applications of nanomedicine in pre-clinical ARDS therapy, highlights the strategies for targeted treatment of lung inflammation, presents the innovative drug delivery systems, and provides inspiration for strengthening the therapeutic effect of nanomedicine-based treatment.

Nanocarriers in the Delivery of Hydroxychloroquine to the Respiratory System: An Alternative to COVID-19

In response to the global outbreak caused by SARS-CoV-2, this article aims to propose the development of nanosystems for the delivery of hydroxychloroquine in the respiratory system to the treatment of COVID-19. A descriptive literature review was conducted, using the descriptors "COVID-19", "Nanotechnology", "Respiratory Syndrome" and "Hydroxychloroquine", in the PubMed, ScienceDirect and SciElo databases. After analyzing the articles according to the inclusion and exclusion criteria, they were divided into 3 sessions: Coronavirus: definitions, classifications and epidemiology, pharmacological aspects of hydroxychloroquine and pharmaceutical nanotechnology in targeting of drugs. We used 131 articles published until July 18, 2020. Hydroxychloroquine seems to promote a reduction in viral load, in vivo studies, preventing the entry of SARS-CoV-2 into lung cells, and the safety of its administration is questioned due to the toxic effects that it can develop, such as retinopathy, hypoglycemia and even cardiotoxicity. Nanosystems for the delivery of drugs in the respiratory system may be a viable alternative for the administration of hydroxychloroquine, which may enhance the therapeutic effect of the drug with a consequent decrease in its toxicity, providing greater safety for implementation in the clinic in the treatment of COVID-19.

Preparation and evaluation of vancomycin spray-dried powders for pulmonary delivery

The aim of the current study was to achieve a dry powder formulation of vancomycin by spray drying whilst evaluating the effect of pH and excipient type and percentage used in formulation on particle characteristics and aerosolization performance. A D-optimal design was applied to optimize the formulation comprising vancomycin and two main excipient groups; a carbohydrate bulking agent (lactose, mannitol or trehalose) and a second excipient (hydroxypropyl beta-cyclodextrin or L-leucine) at pH 4 and 7. The physicochemical properties of particles (size, morphology, crystallinity state, residual moisture content), stability, and aerosolization characteristics were investigated. Using the combination of two excipients increased the fine particle fraction of powder emitted from an Aerolizer^® device at a flow rate of 60 L/min. Hydroxypropyl beta-cyclodextrin showed more potential than L-leucine in aerosolization capabilities. Stability studies over 3 months of storage in 40 °C and 75% relative humidity suggested a good physical stability of the optimized formulation containing 17.39% hydroxypropyl beta-cyclodextrin along with 29.61% trehalose relative to the amount of drug at pH 4. Use of two excipients including trehalose and hydroxypropyl beta-cyclodextrin with a total weight ratio of 47% relative to the amount of drug is appropriate for the preparation of vancomycin dry powder formulation for inhalation.

Nanoparticle Delivery Systems with Cell-Specific Targeting for Pulmonary Diseases

Respiratory disorders are among the most important medical problems threatening human life. The conventional therapeutics for respiratory disorders are hindered by insufficient drug concentrations at pathological lesions, lack of cell-specific targeting, and various biobarriers in the conducting airways and alveoli. To address these critical issues, various nanoparticle delivery systems have been developed to serve as carriers of specific drugs, DNA expression vectors, and RNAs. The unique properties of nanoparticles, including controlled size and distribution, surface functional groups, high payload capacity, and drug release triggering capabilities, are tailored to specific requirements in drug/gene delivery to overcome major delivery barriers in pulmonary diseases. To avoid off-target effects and improve therapeutic efficacy, nanoparticles with high cell-targeting specificity are essential for successful nanoparticle therapies. Furthermore, low toxicity and high degradability of the nanoparticles are among the most important requirements in the nanoparticle designs. In this review, we provide the most up-to-date research and clinical outcomes in nanoparticle therapies for pulmonary diseases. We also address the current critical issues in key areas of pulmonary cell targeting, biosafety and compatibility, and molecular mechanisms for selective cellular uptake.

Multifunctional lipid-based nanocarriers with antibacterial and anti-inflammatory activities for treating MRSA bacteremia in mice

Background

Bacteremia-induced sepsis is a leading cause of mortality in intensive care units. To control a bacterial infection, an immune response is required, but this response might contribute to organ failure. Kidneys are one of the main organs affected by bacteremia. Combination therapies with antibacterial and anti-inflammatory effects may be beneficial in treating bacteremia. This study aimed to develop nanostructured lipid carriers (NLCs) loaded with ciprofloxacin and rolipram that exert a combination of anti-methicillin-resistant Staphylococcus aureus (MRSA) and anti-inflammatory effects. Retinol was incorporated into the nanoparticles to transport retinol-binding protein 4 (RBP4) to the kidneys, which abundantly express RBP receptors. The NLCs were fabricated by high-shear homogenization and sonication, and neutrophils were used as a model to assess their anti-inflammatory effects. Mice were injected with MRSA to establish a model of bacteremia with organ injury.

Results

The mean nanoparticle size and zeta potential of the NLCs were 171 nm and − 39 mV, respectively. Ciprofloxacin (0.05%, w/v) and rolipram (0.02%) achieved encapsulation percentages of 88% and 96%, respectively, in the nanosystems. The minimum bactericidal concentration of free ciprofloxacin against MRSA increased from 1.95 to 15.63 µg/ml when combined with rolipram, indicating a possible drug-drug interaction that reduced the antibacterial effect. Nanoparticle inclusion promoted the anti-MRSA activity of ciprofloxacin according to time-kill curves. The NLCs were found to be largely internalized into neutrophils and exhibited superior superoxide anion inhibition than free drugs. Retinol incorporation into the nanocarriers facilitated their efficient targeting to the kidneys. The NLCs significantly mitigated MRSA burden and elastase distribution in the organs of MRSA-infected animals, and the greatest inhibition was observed in the kidneys. Bacterial clearance and neutrophil infiltration suppression attenuated the bacteremia-induced cytokine overexpression, leading to an improvement in the survival rate from 22% to 67%.

Conclusions

The dual role of our NLCs endowed them with greater efficacy in treating MRSA bacteremia than that of free drugs.

Surface Active Agents and Their Health-Promoting Properties: Molecules of Multifunctional Significance

Surface active agents (SAAs) are molecules with the capacity to adsorb to solid surfaces and/or fluid interfaces, a property that allows them to act as multifunctional ingredients (e.g., wetting and dispersion agents, emulsifiers, foaming and anti-foaming agents, lubricants, etc.) in a widerange of the consumer products of various industrial sectors (e.g., pharmaceuticals, cosmetics, personal care, detergents, food, etc.). Given their widespread utilization, there is a continuously growing interest to explore their role in consumer products (relevant to promoting human health) and how such information can be utilized in order to synthesize better chemical derivatives. In this review article, weaimed to provide updated information on synthetic and biological (biosurfactants) SAAs and their health-promoting properties (e.g., anti-microbial, anti-oxidant, anti-viral, anti-inflammatory, anti-cancer and anti-aging) in an attempt to better define some of the underlying mechanism(s) by which they exert such properties.

Nanotechnology and Early Human Development

The application of nanotechnology, molecular biotechnologies, and nano-sciences for medical purposes has been termed nanomedicine, a promising growing area of medical research. The aim of this paper is to provide an overview of and discuss nanotechnology applications in the early epochs of life, from transplacental transfer to neonatal/pediatric conditions. Diagnostic and therapeutic applications, mainly related to the respiratory tract, the neurosensory system, and infections, are explored and discussed. Preclinical studies show promising results for a variety of conditions, including for the treatment of pregnancy complications and fetal, neonatal, and pediatric diseases. However, given the complexity of the functions and interactions between the placenta and the fetus, and the complex and incompletely understood determinants of tissue growth and differentiation during early life, there is a need for much more data to confirm the safety and efficacy of nanotechnology in this field.

Nano-Based Drug Delivery or Targeting to Eradicate Bacteria for Infection Mitigation: A Review of Recent Advances

Pathogenic bacteria infection is a major public health problem due to the high morbidity and mortality rates, as well as the increased expenditure on patient management. Although there are several options for antimicrobial therapy, their efficacy is limited because of the occurrence of drug-resistant bacteria. Many conventional antibiotics have failed to show significant amelioration in overall survival of infectious patients. Nanomedicine for delivering antibiotics provides an opportunity to improve the efficiency of the antibacterial regimen. Nanosystems used for antibiotic delivery and targeting to infection sites render some benefits over conventional formulations, including increased solubility, enhanced stability, improved epithelium permeability and bioavailability, prolonged antibiotic half-life, tissue targeting, and minimal adverse effects. The nanocarriers' sophisticated material engineering tailors the controllable physicochemical properties of the nanoparticles for bacterial targeting through passive or active targeting. In this review, we highlight the recent progress on the development of antibacterial nanoparticles loaded with antibiotics. We systematically introduce the concepts and amelioration mechanisms of the nanomedical techniques for bacterial eradication. Passive targeting by modulating the nanoparticle structure and the physicochemical properties is an option for efficient drug delivery to the bacteria. In addition, active targeting, such as magnetic hyperthermia induced by iron oxide nanoparticles, is another efficient way to deliver the drugs to the targeted site. The nanoparticles are also designed to respond to the change in environment pH or enzymes to trigger the release of the antibiotics. This article offers an overview of the benefits of antibacterial nanosystems for treating infectious diseases.

Suppression of neutrophilic inflammation can be modulated by the droplet size of anti-inflammatory nanoemulsions

Aim: We aimed to develop nanoemulsions containing phosphodiesterase 4 inhibitor rolipram with different droplet sizes, to evaluate the anti-inflammatory effect against activated neutrophils and a related lung injury. Materials & methods: We prepared nanoemulsions of three different sizes, 68, 133 and 188 nm. Results: The nanoemulsion inhibited the superoxide anion but not elastase release in primary human neutrophils. The large-sized nanoemulsions were mostly internalized by neutrophils, resulting in the reduction of intracellular Ca²⁺ half-life. The peripheral organ distribution of near-infrared dye-tagged nanoemulsions increased, following the decrease in droplet diameter. Rolipram entrapment into intravenous nanoemulsions ameliorated pulmonary inflammation. The smallest droplet size showed improvement, compared with the largest size. Conclusion: We established a foundation for the development of nanoemulsions against inflamed lung disease.

Oleic acid-based nanosystems for mitigating acute respiratory distress syndrome in mice through neutrophil suppression: how the particulate size affects therapeutic efficiency

Background

Oleic acid (OA) is reported to show anti-inflammatory activity toward activated neutrophils. It is also an important material in nanoparticles for increased stability and cellular internalization. We aimed to evaluate the anti-inflammatory activity of injectable OA-based nanoparticles for treating lung injury. Different sizes of nanocarriers were prepared to explore the effect of nanoparticulate size on inflammation inhibition.

Results

The nanoparticles were fabricated with the mean diameters of 105, 153, and 225 nm. The nanocarriers were ingested by isolated human neutrophils during a 5-min period, with the smaller sizes exhibiting greater uptake. The size reduction led to the decrease of cell viability and the intracellular calcium level. The OA-loaded nanosystems dose-dependently suppressed the superoxide anion and elastase produced by the stimulated neutrophils. The inhibition level was comparable for the nanoparticles of different sizes. In the ex vivo biodistribution study, the pulmonary accumulation of nanoparticles increased following the increase of particle size. The nanocarriers were mainly excreted by the liver and bile clearance. Mice were exposed to intratracheal lipopolysaccharide (LPS) to induce acute respiratory distress syndrome (ARDS), like lung damage. The lipid-based nanocarriers mitigated myeloperoxidase (MPO) and cytokines more effectively as compared to OA solution. The larger nanoparticles displayed greater reduction on MPO, TNF-α, and IL-6 than the smaller ones. The histology confirmed the decreased pulmonary neutrophil recruitment and lung-architecture damage after intravenous administration of larger nanoparticles.

Conclusions

Nanoparticulate size, an essential property governing the anti-inflammatory effect and lung-injury therapy, had different effects on activated neutrophil inhibition and in vivo therapeutic efficacy.

The atopic dermatitis-like lesion and the associated MRSA infection and barrier dysfunction can be alleviated by 2,4-dimethoxy-6-methylbenzene-1,3-diol from Antrodia camphorata

BACKGROUND

Atopic dermatitis (AD) is an inflammatory skin disease with an associated barrier dysfunction and Staphylococcus aureus infection. The mainstay steroid and calcineurin inhibitor therapy shows some adverse effects. 2,4-Dimethoxy-6-methylbenzene-1,3-diol (DMD) is a benzenoid isolated from Antrodia camphorata.

OBJECTIVE

We investigated the inhibitory effect of DMD on methicillin-resistant S. aureus (MRSA), the chemokine production in stimulated keratinocytes, and the AD-like lesion found in ovalbumin (OVA)-sensitized mice.

METHODS

The antimicrobial effect and cutaneous barrier function were evaluated using an in vitro culture model and an in vivo mouse model of AD-like skin.

RESULTS

DMD exhibited a comparative minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against MRSA with nalidixic acid, a conventional antibiotic. The MIC and MBC for DMD was 78.1 and 156.3 μg/ml, respectively. DMD also showed the ability to eliminate the clinical bacteria isolates with resistance to methicillin and vancomycin. The DNA polymerase and gyrase inhibition evoked by DMD for bacterial lethality was proposed. In the activated keratinocytes, DMD stopped the upregulation of chemokines (CCL5 and CCL17) and increased the expression of differentiation proteins (filaggrin, involucrin, and integrin β-1). Topical application of DMD facilely penetrated into the skin, with AD-like skin displaying 2.5-fold greater permeation than healthy skin. The in vivo assessment using the mouse model with OVA sensitization and MRSA inoculation revealed a reduction of transepidermal water loss (TEWL) and bacterial burden by DMD by about 2- and 100-fold, respectively. Differentiation proteins were also restored after topical DMD delivery.

CONCLUSION

Our data demonstrated an advanced concept of AD treatment by combined barrier repair and bacterial eradication with a sole agent for ameliorating the overall complications.