An investigation into the interactions of gold nanoparticles and anti-arthritic drugs with macrophages, and their reactivity towards thioredoxin reductase

nanoGold and µGold inhibit autoimmune inflammation: a review

The newest data on metallic gold have placed the noble metal central in the fight for the safe treatment of autoimmune inflammation. There are two different ways to use gold for the treatment of inflammation: gold microparticles > 20 µm and gold nanoparticles. The injection of gold microparticles (µGold) is a purely local therapy. µGold particles stay put where injected, and gold ions released from them are relatively few and taken up by cells within a sphere of only a few millimeters in diameter from their origin particles. The macrophage-induced release of gold ions may continue for years. Injection of gold nanoparticles (nanoGold), on the other hand, is spread throughout the whole body, and the bio-released gold ions, therefore, affect multitudes of cells all over the body, as when using gold-containing drugs such as Myocrisin. Since macrophages and other phagocytotic cells take up and transport nanoGold and remove it after a short period, repeated treatment is necessary. This review describes the details of the cellular mechanisms that lead to the bio-release of gold ions in µGold and nanoGold.

Comparison of the structure and activity of thioredoxin 2 and thioredoxin 1 from Acinetobacter baumannii

Thioredoxin (Trx) is essential in a redox-control system, with many bacteria containing two Trxs: Trx1 and Trx2. Due to a Trx system's critical function, Trxs are targets for novel antibiotics. Here, a 1.20 Å high-resolution structure of Trx2 from Acinetobacter baumannii (abTrx2), an antibiotic resistant pathogenic superbug, is elucidated. By comparing Trx1 and Trx2, it is revealed that the two Trxs possess similar activity, although Trx2 contains an additional N-terminal zinc-finger domain and exhibits more flexible properties in solution. Finally, it is shown that the Trx2 zinc-finger domain might be rotatable and that proper zinc coordination at the zinc-finger domain is critical to abTrx2 activity. This study enhances understanding of the Trx system and will facilitate the design of novel antibiotics.

Recent advances in nanoparticle-based drug delivery systems for rheumatoid arthritis treatment

Nanotechnology has increasingly emerged as a promising tool for exploring new approaches, from treating complex conditions to early detection of the onset of multiple disease states. Tailored designer nanoparticles can now more comprehensively interact with their cellular targets and various pathogens due to a similar size range and tunable surface properties. The basic goal of drug delivery is to employ pharmaceuticals only where they are needed, with as few adverse effects and off-target consequences as possible. Rheumatoid arthritis (RA) is a chronic inflammatory illness that leads to progressive loss of bone and cartilage, resulting in acute impairment, decreased life expectancy, and increased death rates. Recent advancements in treatment have significantly slowed the progression of the disease and improved the lives of many RA sufferers. Some patients, on the other hand, attain or maintain illness remission without needing to continue immunosuppressive therapy. Furthermore, a large percentage of patients do not respond to current treatments or acquire tolerance to them. As a result, novel medication options for RA therapy are still needed. Nanocarriers, unlike standard medications, are fabricated to transport drugs directly to the location of joint inflammation, evading systemic and negative effects. As a result, researchers are reconsidering medicines that were previously thought to be too hazardous for systemic delivery. This article gives an overview of contemporary nanotechnology-based tactics for treating rheumatoid arthritis, as well as how the nanotherapeutic regimen could be enhanced in the future.

Treatment with silica-gold nanostructures decreases inflammation-related gene expression in collagen-induced arthritis

Gold salts have been used to treat rheumatoid arthritis (RA) since the 1940s, and, with advances in nanotechnology, the use of nanogold provides multiple options for anti-inflammatory therapies. This paper presents the synthesis and characterization of silica-gold nanostructures (SGNs) and their therapeutic effect in collagen-induced arthritis (CIA) in DBA/1 mice. At the end of the treatment, the synovial membranes, kidneys, livers, and spleens were dissected and analyzed by inductively coupled plasma mass spectroscopy (ICP) showing less than 0.0001 and 0.1% of the administered doses of Au and Si, respectively. Remains of the SGNs were visually identified in the synovial membrane by scanning electron microscopy (SEM), and the bone density of the hind paws was observed by computerized tomography (CT) indicating a reduction of porosity in the CIA-experimental group. The DNA microarray analysis carried out with RNA obtained from the hind paws showed 2628 differentially expressed genes (DEGs) by SGNs. The bioinformatic analysis showed that DEGs were significantly associated with several inflammatory signalling pathways including chemokines, cytokine-cytokine receptor interaction, PI3K-Akt, TNF, IL-17, NFκβ, MAPK, and RA. SGNs downregulated relevant inflammatory genes in the arthritic joints, including Tnf, Ifng, Il6, and Cxcl5; immunohistochemistry (IHC) confirmed the reduction of TNFα, IL-6, NFκβ, and VEGF in the joints due to the effect of SGNs. TNFα and IL-6 were also reduced in the serum of DBA/1 mice treated with SGNs.

Multimodal Potentials of Gold Nanoparticles for Bone Tissue Engineering and Regenerative Medicine: Avenues and Prospects

Osseous tissue repair has advanced due to the introduction of tissue engineering. The key elements required while engineering new tissues involve scaffolds, cells, and bioactive cues. The macrostructural to the nanostructural framework of such complex tissue has engrossed the intervention of nanotechnology for efficient neo-bone formation. Gold nanoparticles (GNPs) have recently gained interest in bone tissue regeneration due to their multimodal functionality. They are proven to modulate the properties of scaffolds and the osteogenic cells significantly. GNPs also influence different metabolic functions within the body, which directly or indirectly govern the mechanism of bone regeneration. Therefore, this review highlights nanoparticle-mediated osteogenic development, focusing on different aspects of GNPs ranging from scaffold modulation to cellular stimulation. The toxic aspects of gold nanoparticles studied so far are critically explicated, while further insight into the advancements and prospects of these nanoparticles in bone regeneration is also highlighted.

A Clinical Study to Evaluate the Safety and Efficacy of Oral Administration of Microscopic Dose Gold Nanoparticle (AuNP) on Knee Joint Health and Function in Arthritis Patients

The purpose of this clinical study was to determine whether gold nanoparticle (AuNP) supplementation at a dosage of 0.34 mg elemental gold per day can improve knee joint health, function, and quality of life for arthritis patients. A total of 51 participants (24 male and 27 female, age 62.1 ± 13.1) were followed for 20 weeks through a three-phase longitudinal study. Both subjective and objective parameters were used to measure changes in joint health and function, as well as quality of life. The study found patients' Knee injury and Osteoarthritis Outcome Score (KOOS) improved with statistical significance. It was reported that 71.42% of the cohort experienced improvements in their perceived knee pain and 61.22% with improvements in knee stiffness. Majority of objective measurements such as pain with range of motion and specific exercises requiring proper knee health and function did not show statistically significant improvement but did show a positive improving trend in support of AuNP supplement. Study cohort showed statistically significant improvements in two specific exercises: sit-to-stand and single-leg squat. By the end of the study, 70% of the study cohort indicated that they would continue to take the supplement even after the study concluded. Though the study has limitations and is not definitely conclusive, it was the first clinical study to show that oral micro-dosage of AuNP as low as 0.34 mg daily is safe and effective for both rheumatoid arthritis and osteoarthritis patients. This study opened way for the use of AuNP in both clinical and daily settings to improve joint health and function for both average and athletic users.

Quantitative Chemoproteomic Profiling of Targets of Au(I) Complexes by Competitive Activity-Based Protein Profiling

Owing to the encouraging pharmacological action and acceptable toxicity profile, Au(I) complexes have attracted growing interest in the application of disease treatment. In order to investigate their potential target proteins and related bioinformation, herein, we screened four Au(I) complexes and explored the binding proteins utilizing a competitive activity-based protein profiling (ABPP) strategy, including identification experiments and reactivity classification experiments, which offers a simple and robust method to identify the target proteins of Au(I) complexes. We quantified the target proteins of the four Au(I) complexes and found that most of proteins were associated with cancer. In addition, the newly Au(I)-binding proteins and biological gold-protein interaction pathways were exhibited. Furthermore, we estimated the correlation between target proteins of Au(I) complexes and various cancers, which will promote the development of the gold anticancer drugs.

Conception and evaluation of fluorescent phosphine-gold complexes: from synthesis to in vivo investigations

A phosphine gold(I) and phosphine-phosphonium gold(I) complexes bearing a fluorescent coumarin moiety were synthesized and characterized. Both complexes displayed interesting photophysical properties: good molar absorption coefficient, good quantum yield of fluorescence, and ability to be tracked in vitro thanks to two-photon imaging. Their in vitro and in vivo biological properties were evaluated onto cancer cell lines both human and murine and into CT26 tumor-bearing BALB/c mice. They displayed moderate to strong antiproliferative properties and the phosphine-phosphonium gold(I) complex induced significant in vivo anti-cancer effect.

Methotrexate-loaded folic acid of solid-phase synthesis conjugated gold nanoparticles targeted treatment for rheumatoid arthritis

PURPOSE

Methotrexate (MTX) is a first-line drug for rheumatoid arthritis (RA). Targeting of MTX to inflamed joints is essential to the prevention of potential toxicity and improving therapeutic effects. Gold nanoparticles (GNPs) are characterized by controllable particle sizes and good biocompatibilities, therefore, they are promising drug delivery systems. We aimed at developing a GNPs drug delivery system incorporating MTX and folic acid (FA) with strong efficacies against RA.

METHODS

MTX-Cys-FA was synthesized through solid-phase organic synthesis. Then, it was coupled with sulfhydryl groups in GNPs, thereby successfully preparing a GNPs/MTX-Cys-FA nanoconjugate with targeting properties. Physical and chemical techniques were used to characterize it. Moreover, we conducted its stability, release, pharmacokinetics, biodistribution and cell cytotoxicity, cell uptake, cell migration, as well as its therapeutic effect on CIA rats. The histopathology was conducted to investigate anti-RA effects of GNPs/MTX-Cys-FA nanoconjugates.

RESULTS

The GNPs/MTX-Cys-FA nanoconjugate exhibited a spherical appearance, had a particle size of 103.06 nm, a zeta potential of -33.68 mV, drug loading capacity of 11.04 %, and an encapsulation efficiency of 73.61%. Cytotoxicity experiments revealed that GNPs had good biocompatibilities while GNPs/MTX-Cys-FA exhibited excellent drug-delivery abilities. Cell uptake and migration experiment showed that nanoconjugates containing FA by LPS activated mouse mononuclear macrophages (RAW264.7) was significantly increased, and they exerted significant inhibitory effects on human fibroblast-like synoviocytes (HFLS) of RA (p<0.01). In addition, the nanoconjugate prolonged blood circulation time of MTX in collagen-induced arthritis (CIA) rats (p<0.01), enhanced MTX accumulation in inflamed joints (p<0.01), enhanced their therapeutic effects (p<0.01), and reduced toxicity to major organs (p<0.01).

CONCLUSION

GNPs/MTX-Cys-FA nanoconjugates provide effective approaches for RA targeted therapeutic strategies.

Gold Nanoparticles: Multifaceted Roles in the Management of Autoimmune Disorders

Gold nanoparticles (GNPs) have been recently applied for various diagnostic and therapeutic purposes. The unique properties of these nanoparticles (NPs), such as relative ease of synthesis in various sizes, shapes and charges, stability, high drug-loading capacity and relative availability for modification accompanied by non-cytotoxicity and biocompatibility, make them an ideal field of research in bio-nanotechnology. Moreover, their potential to alleviate various inflammatory factors, nitrite species, and reactive oxygen production and the capacity to deliver therapeutic agents has attracted attention for further studies in inflammatory and autoimmune disorders. Furthermore, the characteristics of GNPs and surface modification can modulate their toxicity, biodistribution, biocompatibility, and effects. This review discusses in vitro and in vivo effects of GNPs and their functionalized forms in managing various autoimmune disorders (Ads) such as rheumatoid arthritis, type 1 diabetes, and multiple sclerosis.

Nanomaterials Manipulate Macrophages for Rheumatoid Arthritis Treatment

Rheumatoid arthritis (RA) is a chronic, progressive, and systemic inflammatory autoimmune disease, characterized by synovial inflammation, synovial lining hyperplasia and inflammatory cell infiltration, autoantibody production, and cartilage/bone destruction. Macrophages are crucial effector cells in the pathological process of RA, which can interact with T, B, and fibroblast-like synovial cells to produce large amounts of cytokines, chemokines, digestive enzymes, prostaglandins, and reactive oxygen species to accelerate bone destruction. Therefore, the use of nanomaterials to target macrophages has far-reaching therapeutic implications for RA. A number of limitations exist in the current clinical therapy for patients with RA, including severe side effects and poor selectivity, as well as the need for frequent administration of therapeutic agents and high doses of medication. These challenges have encouraged the development of targeting drug delivery systems and their application in the treatment of RA. Recently, obvious therapeutic effects on RA were observed following the use of various types of nanomaterials to manipulate macrophages through intravenous injection (active or passive targeting), oral administration, percutaneous absorption, intraperitoneal injection, and intra-articular injection, which offers several advantages, such as high-precision targeting of the macrophages and synovial tissue of the joint. In this review, the mechanisms involved in the manipulation of macrophages by nanomaterials are analyzed, and the prospect of clinical application is also discussed. The objective of this article was to provide a reference for the ongoing research concerning the treatment of RA based on the targeting of macrophages.

Crystal structure of the cofactor-free form of thioredoxin reductase from Acinetobacter baumannii

Thioredoxin reductase (TrxR) is a central component in the thioredoxin system by involving in catalyzing the reduction of thioredoxin, which is critical for organism survival. Because this system is essential, it is a promising target for novel antimicrobial agents. Herein, we solved the 1.9 Å high-resolution structure of TrxR from Acinetobacter baumannii Thioredoxin reductase (AbTrxR), which is a Gram-negative, pathogenic bacterium and a drug-resistant superbug. AbTrxR was cofactor-free and formed a dimer in solution. AbTrxR contained a longer dimerization loop2 and a shorter β₇ -β₈ connecting loop than other TrxRs. AbTrxR cofactor-free form exhibited a flavin-oxidizing (FO) conformation, whose NADPH domain was located close to the dimeric interface. This structural information might be helpful for development of new antibiotic agents targeting superbugs.

Near-infrared emitting fluorescent homobimetallic gold(I) complexes displaying promising in vitro and in vivo therapeutic properties

Three near-infrared (NIR-I) optical theranostic systems were synthesized, characterized and studied in vitro and in vivo. These original homo-bimetallic gold(I)-based aza-BODIPY complexes proved to be trackable through near-infrared optical imaging in cells and in mice. They display anti-proliferative properties in micromolar range against human and murine cancer cell lines (4T1, MDA-MB-231, CT26, and SW480). Moreover, the injection of the most promising theranostic agent in CT26 tumor-bearing BALB/c mice induced a significant anti-cancer activity.

In-vitro and in-vivo monitoring of gold(III) ions from intermediate metabolite of sodium aurothiomalate through water-soluble ruthenium (II) complex-based luminescent probe

Real-time monitoring of drug metabolism in vivo is of great significance to drug development and toxicology research. The purpose of this study is to establish a rapid and visual in vivo detection method for the detection of an intermediate metabolite of the gold (I) drug. Gold (I) drugs such as sodium aurothiomalate (AuTM) have anti-inflammatory effects in the treatment of rheumatoid arthritis. Gold(III) ions (Au³⁺) are the intermediate metabolite of gold medicine, and they are also the leading factor of side effects in the treatment of patients. However, the rapid reduction of Au³⁺ to Au⁺ by thiol proteins in organisms limits the in-depth study of metabolism of gold drugs in vivo. Here we describe a luminescence Au³⁺ probe (RA) based on ruthenium (II) complex for detecting Au³⁺ in vitro and in vivo. RA with large Stokes shift, good water solubility and biocompatibility was successfully applied to detect Au³⁺ in living cells and vivo by luminescence imaging, and to trap the fluctuation of Au³⁺ level produced by gold (I) medicine. More importantly, the luminescent probe was used to the detection of the intermediate metabolites of gold (I) drugs for the first time. Overall, this work offers a new detection tool/method for a deeper study of gold (I) drugs metabolite.

Uptake quantification of gold nanoparticles inside of cancer cells using high order image correlation spectroscopy

The application of gold nanoparticles (AuNPs) in cancer therapeutics and diagnostics has recently reached a clinical level. Functional use of the AuNP in theranostics first requires effective uptake into the cells, but accurate quantification of AuNPs cellular uptake in real-time is still a challenge due to the destructive nature of existing characterization methods. The optical imaging-based quantification method is highly desirable. Here, we propose the use of high-order image correlation spectroscopy (HICS) as an optical imaging-based nanoparticle quantification technique. Coupled with dark field microscopy (DFM), a non-destructive and easy quantification method could be achieved. We demonstrate HICS analysis on 80 nm AuNPs coated with cetyltrimethylammonium bromide (CTAB) uptake in HeLa cells to calculate the percentage of aggregate species (dimer) in the total uptake and their relative scattering quantum yield inside the cells, the details of which are not available with other quantification techniques. The total particle uptake kinetics measured were in a reasonable agreement with the literature.

Activity of Auranofin against Multiple Genotypes of Naegleria fowleri and Its Synergistic Effect with Amphotericin B In Vitro

Primary amebic meningoencephalitis, caused by brain infection with a free-living ameba, Naegleria fowleri, leads to extensive inflammation of the brain and death within 3-7 days after symptoms begin. Treatment of primary amebic meningoencephalitis relies on amphotericin B in combination with other drugs, but use of amphotericin B is associated with severe adverse effects. Despite a fatality rate of over 97%, economic incentive to invest in development of antiamebic drugs by the pharmaceutical industry is lacking. Development of safe and rapidly acting drugs remains a critical unmet need to avert future deaths. Since FDA-approved anti-inflammatory and antiarthritic drug auranofin is a known inhibitor of selenoprotein synthesis and thioredoxin reductase and the genome of N. fowleri encodes genes for both selenocysteine biosynthesis and thioredoxin reductases, we tested the effect of auranofin against N. fowleri strains of different genotypes from the USA, Europe, and Australia. Auranofin was equipotent against all tested strains with an EC₅₀ of 1-2 μM. Our growth inhibition study at different time points demonstrated that auranofin is fast-acting, and ∼90% growth inhibition was achieved within 16 h of drug exposure. A short exposure of N. fowleri to auranofin led to the accumulation of intracellular reactive oxygen species. This is consistent with auranofin's role in inhibiting antioxidant pathways. Further, combination of auranofin and amphotericin B led to 95% of growth inhibition with 2-9-fold dose reduction for amphotericin B and 3-20-fold dose reduction for auranofin. Auranofin has the potential to be repurposed for the treatment of primary amebic meningoencephalitis.

Targeted and triple therapy-based liposomes for enhanced treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease that is currently incurable. Clinical practice has shown significant benefits of combined therapies for RA treatment. This study aims to develop and demonstrate an efficient triple therapy for RA in vitro and in vivo. Three anti-inflammatory agents, NF-κB decoy oligodeoxynucleotides (ODNs), gold nanorods (GNRs), and dexamethasone (DEX), were encapsulated into folate (FA) modified liposomes (FA-lip(DEX + GNRs/ODNs)). The FA-lip(DEX + GNRs/ODNs) showed favorable physicochemical properties and efficient intracellular uptake by inflamed macrophages. Combined with laser irradiation, FA-lip(DEX + GNRs/ODNs) greatly reduced the secretion of proinflammatory proteins and oxidative factors in vitro. In adjuvant-induced arthritis (AIA) mice, FA-lip(DEX + GNRs/ODNs) achieved prolonged and enhanced accumulation at inflamed paws. FA-lip(DEX + GNRs/ODNs) + laser treatment reduced clinical arthritis scores and serum cytokine levels and protected cartilage. In summary, the triple therapy demonstrated significantly enhanced anti-inflammatory efficacy and is a promising strategy to treat RA via combined anti-inflammatory mechanisms.

Protecting the Normal Physiological Functions of Articular and Periarticular Structures by Aurum Nanoparticle-Based Formulations: an Up-to-Date Insight

Taking the articular and periarticular structures as a litmus test for gold-based nanoformulations, the potential of gold nanoparticles in protecting the normal physiological functions of these structures particularly in geriatric patients is one of the research areas of current interest. Aside from its use to make the traditional and fashionable ornaments for human usage, the gold metal is also known for its rich therapeutic activity. This is especially true when the gold is converted from its bulk form into nanosized form before its administering into the human body. Since it is the age of nanocomponents in medical and pharmaceutical research areas, this review is therefore mainly focused on nanoparticulate systems consisting of aurum. Accumulating research reports nevertheless show concrete evidence indicating the potential of gold-based nanoformulations to manage joint syndromes such as osteoarthritis and rheumatoid arthritis. This review embarks from preparation techniques and characterization methods to therapeutical application potentials of gold-based nanoformulations.

Gold nanoparticles: New routes across old boundaries

In recent years, gold nanoparticles have emerged as unique non-invasive drug carriers for targeting drugs to their site of action. Their site specificity has helped in increasing drugs' efficacy at lower dose as well as reduction in their side effects. Moreover, their excellent optical properties and small size offer their utilization as diagnostic tools to diagnose tumors as well as other diseases. This review focuses on various approaches that have been used in last several years for preparation of gold nanoparticles, their characterization techniques and theranostic applications. Their toxicity related aspects are also highlighted. Gold nanoparticles are useful as theranostic agents, owing to their small size, biocompatible nature, size dependent physical, chemical and optical properties etc. However, the challenges associated with these nanoparticles such as scale up, cost, low drug payload, toxicity and stability have been the major impediments in their commercialization. The review looks into all these critical issues and identifies the possibilities to overcome these challenges for successful positioning of metallic nanoparticles in market.

Structure, Mechanism, and Inhibition of Aspergillus fumigatus Thioredoxin Reductase

Aspergillus fumigatus infections are associated with high mortality rates and high treatment costs. Limited available antifungals and increasing antifungal resistance highlight an urgent need for new antifungals. Thioredoxin reductase (TrxR) is essential for maintaining redox homeostasis and presents as a promising target for novel antifungals. We show that ebselen [2-phenyl-1,2-benzoselenazol-3(2H)-one] is an inhibitor of A. fumigatus TrxR (K_i = 0.22 μM) and inhibits growth of Aspergillus spp., with in vitro MIC values of 16 to 64 µg/ml. Mass spectrometry analysis demonstrates that ebselen interacts covalently with a catalytic cysteine of TrxR, Cys148. We also present the X-ray crystal structure of A. fumigatus TrxR and use in silico modeling of the enzyme-inhibitor complex to outline key molecular interactions. This provides a scaffold for future design of potent and selective antifungal drugs that target TrxR, improving the potency of ebselen toward inhbition of A. fumigatus growth.

A Precautionary Approach to Guide the Use of Transition Metal-Based Nanotechnology to Prevent Orthopedic Infections

The increase of multidrug-resistant bacteria remains a global concern. Among the proposed strategies, the use of nanoparticles (NPs) alone or associated with orthopedic implants represents a promising solution. NPs are well-known for their antimicrobial effects, induced by their size, shape, charge, concentration and reactive oxygen species (ROS) generation. However, this non-specific cytotoxic potential is a powerful weapon effective against almost all microorganisms, but also against eukaryotic cells, raising concerns related to their safe use. Among the analyzed transition metals, silver is the most investigated element due to its antimicrobial properties per se or as NPs; however, its toxicity raises questions about its biosafety. Even though it has milder antimicrobial and cytotoxic activity, TiO₂ needs to be exposed to UV light to be activated, thus limiting its use conjugated to orthopedic devices. By contrast, gold has a good balance between antimicrobial activity as an NP and cytocompatibility because of its inability to generate ROS. Nevertheless, although the toxicity and persistence of NPs within filter organs are not well verified, nowadays, several basic research on NP development and potential uses as antimicrobial weapons is reported, overemphasizing NPs potentialities, but without any existing potential of translation in clinics. This analysis cautions readers with respect to regulation in advancing the development and use of NPs. Hopefully, future works in vivo and clinical trials will support and regulate the use of nano-coatings to guarantee safer use of this promising approach against antibiotic-resistant microorganisms.

Orally administered gold nanoparticles protect against colitis by attenuating Toll-like receptor 4- and reactive oxygen/nitrogen species-mediated inflammatory responses but could induce gut dysbiosis in mice

Background

Gold nanoparticles (AuNPs) are attracting interest as potential therapeutic agents to treat inflammatory diseases, but their anti-inflammatory mechanism of action is not clear yet. In addition, the effect of orally administered AuNPs on gut microbiota has been overlooked so far. Here, we evaluated the therapeutic and gut microbiota-modulating effects, as well as the anti-inflammatory paradigm, of AuNPs with three different coatings and five difference sizes in experimental mouse colitis and RAW264.7 macrophages.

Results

Citrate- and polyvinylpyrrolidone (PVP)-stabilized 5-nm AuNPs (Au-5 nm/Citrate and Au-5 nm/PVP) and tannic acid (TA)-stabilized 5-, 10-, 15-, 30- and 60-nm AuNPs were intragastrically administered to C57BL/6 mice daily for 8 days during and after 5-day dextran sodium sulfate exposure. Clinical signs and colon histopathology revealed more marked anti-colitis effects by oral administration of Au-5 nm/Citrate and Au-5 nm/PVP, when compared to TA-stabilized AuNPs. Based on colonic myeloperoxidase activity, colonic and peripheral levels of interleukin-6 and tumor necrosis factor-α, and peripheral counts of leukocyte and lymphocyte, Au-5 nm/Citrate and Au-5 nm/PVP attenuated colonic and systemic inflammation more effectively than TA-stabilized AuNPs. High-throughput sequencing of fecal 16S rRNA indicated that AuNPs could induce gut dysbiosis in mice by decreasing the α-diversity, the Firmicutes/Bacteroidetes ratio, certain short-chain fatty acid-producing bacteria and Lactobacillus. Based on in vitro studies using RAW264.7 cells and electron spin resonance oximetry, AuNPs inhibited lipopolysaccharide (LPS)-triggered inducible nitric oxide (NO) synthase expression and NO production via reduction of Toll-like receptor 4 (TLR4), and attenuated LPS-induced nuclear factor kappa beta activation and proinflammatory cytokine production via both TLR4 reduction and catalytic detoxification of peroxynitrite and hydrogen peroxide.

Conclusions

AuNPs have promising potential as anti-inflammatory agents; however, their therapeutic applications via the oral route may have a negative impact on the gut microbiota.

Electronic supplementary material

The online version of this article (10.1186/s12951-018-0415-5) contains supplementary material, which is available to authorized users.

Probing Cellular Processes Using Engineered Nanoparticles

Nanoparticles, the building blocks of nanotechnology, have been widely utilized in various biomedical applications, such as detection, diagnosis, imaging, and therapy. However, another emerging, albeit under-represented, area is the employment of nanoparticles as tools to understand cellular processes (e.g., oxidative stress-induced signaling cascades). Such investigations have enormous potential to characterize a disease from a different perspective and unravel some new features that otherwise would have remained a mystery. In this review, we summarize the intrinsic biological properties of unmodified as well surface modified nanoparticles and discuss how such properties could be utilized to interrogate biological processes and provide a perspective for future evolution of this field.

Gold nanoparticles, radiations and the immune system: Current insights into the physical mechanisms and the biological interactions of this new alliance towards cancer therapy

Considering both cancer's serious impact on public health and the side effects of cancer treatments, strategies towards targeted cancer therapy have lately gained considerable interest. Employment of gold nanoparticles (GNPs), in combination with ionizing and non-ionizing radiations, has been shown to improve the effect of radiation treatment significantly. GNPs, as high-Z particles, possess the ability to absorb ionizing radiation and enhance the deposited dose within the targeted tumors. Furthermore, they can convert non-ionizing radiation into heat, due to plasmon resonance, leading to hyperthermic damage to cancer cells. These observations, also supported by experimental evidence both in vitro and in vivo systems, reveal the capacity of GNPs to act as radiosensitizers for different types of radiation. In addition, they can be chemically modified to selectively target tumors, which renders them suitable for future cancer treatment therapies. Herein, a current review of the latest data on the physical properties of GNPs and their effects on GNP circulation time, biodistribution and clearance, as well as their interactions with plasma proteins and the immune system, is presented. Emphasis is also given with an in depth discussion on the underlying physical and biological mechanisms of radiosensitization. Furthermore, simulation data are provided on the use of GNPs in photothermal therapy upon non-ionizing laser irradiation treatment. Finally, the results obtained from the application of GNPs at clinical trials and pre-clinical experiments in vivo are reported.

Effects of Gold Nanoparticles and Gold Anti-Arthritic Compounds on Inflammation Marker Expression in Macrophages

The ability of aurothiomalate and auranofin to alter the production of several cellular mediators of inflammation by RAW264.7 macrophages, was compared with each other and that of gold nanoparticles (Au NPs). Addition of auranofin was found to have a pronounced ability to lower the production of reactive nitrogen and oxygen species (RNS and ROS respectively), as well as interleukin-10 (IL-10) and tumour necrosis factor (TNF), by macrophages that were subsequently treated with lipopolysaccharide (LPS) to stimulate production of the mediators. In contrast, prior treatment of the cells with either aurothiomalate or Au NPs had either little or no significant effect on production of RNS and ROS. Treatment of the macrophages with Au NPs had a small effect on production of TNF by cells that were subsequently stimulated with LPS; however, the effect was much smaller than that elicited by auranofin. Similarly, aurothiomalate had a small but significant effect on production of IL-10. Varying the size of the Au NPs or the identity of the protective sheath surrounding the nanoparticles did not have a significant effect on the production of RNS or ROS by LPS-stimulated macrophages. The results of some of these investigations are discussed in the light of other studies reported in the literature. In addition, results obtained by scanning electron microscopy and energy-dispersive X-ray spectroscopy are presented that provide evidence for the accumulation of gold within macrophages exposed to Au NPs.

Nanoparticles and direct immunosuppression

Targeting the immune system with nanomaterials is an intensely active area of research. Specifically, the capability to induce immunosuppression is a promising complement for drug delivery and regenerative medicine therapies. Many novel strategies for immunosuppression rely on nanoparticles as delivery vehicles for small-molecule immunosuppressive compounds. As a consequence, efforts in understanding the mechanisms in which nanoparticles directly interact with the immune system have been overshadowed. The immunological activity of nanoparticles is dependent on the physiochemical properties of the nanoparticles and its subsequent cellular internalization. As the underlying factors for these reactions are elucidated, more nanoparticles may be engineered and evaluated for inducing immunosuppression and complementing immunosuppressive drugs. This review will briefly summarize the state-of-the-art and developments in understanding how nanoparticles induce immunosuppressive responses, compare the inherent properties of nanomaterials which induce these immunological reactions, and comment on the potential for using nanomaterials to modulate and control the immune system.

Utilization of nanoparticle technology in rheumatoid arthritis treatment

Rheumatoid arthritis (RA) is one of the common and severe autoimmune diseases related to joints. This chronic autoimmune inflammatory disease, leads to functional limitation and reduced quality of life, since as there is bone and cartilage destruction, joint swelling and pain. Current advances and new treatment approaches have considerably postponed disease progression and improved the quality of life for many patients. In spite of major advances in therapeutic options, restrictions on the routes of administration and the necessity for frequent and long-term dosing often result in systemic adverse effects and patient non-compliance. Unlike usual drugs, nanoparticle systems are planned to deliver therapeutic agents especially to inflamed synovium, so avoiding systemic and unpleasant effects. The present review discusses about some of the most successful drugs in RA therapy and their side effects and also focuses on key design parameters of RA-targeted nanotechnology-based strategies for improving RA therapies.

Nanomedicine delivers promising treatments for rheumatoid arthritis

An increased understanding in the pathophysiology of chronic inflammatory diseases, such as rheumatoid arthritis, reveals that the diseased tissue and the increased presence of macrophages and other overexpressed molecules within the tissue can be exploited to enhance the delivery of nanomedicine. Nanomedicine can passively accumulate into chronic inflammatory tissues via the enhanced permeability and retention phenomenon, or be surface conjugated with a ligand to actively bind to receptors overexpressed by cells within chronic inflammatory tissues, leading to increased efficacy and reduced systemic side-effects. This review highlights the research conducted over the past decade on using nanomedicine for potential treatment of rheumatoid arthritis and summarizes some of the major findings and promising opportunities on using nanomedicine to treat this prevalent and chronic disease.