Enhancement of lipopolysaccharide-induced nitric oxide and interleukin-6 production by PEGylated gold nanoparticles in RAW264.7 cells

Gold Nanoparticles (AuNPs)-Toxicity, Safety and Green Synthesis: A Critical Review

In recent years, the extensive exploration of Gold Nanoparticles (AuNPs) has captivated the scientific community due to their versatile applications across various industries. With sizes typically ranging from 1 to 100 nm, AuNPs have emerged as promising entities for innovative technologies. This article comprehensively reviews recent advancements in AuNPs research, encompassing synthesis methodologies, diverse applications, and crucial insights into their toxicological profiles. Synthesis techniques for AuNPs span physical, chemical, and biological routes, focusing on eco-friendly "green synthesis" approaches. A critical examination of physical and chemical methods reveals their limitations, including high costs and the potential toxicity associated with using chemicals. Moreover, this article investigates the biosafety implications of AuNPs, shedding light on their potential toxic effects on cellular, tissue, and organ levels. By synthesizing key findings, this review underscores the pressing need for a thorough understanding of AuNPs toxicities, providing essential insights for safety assessment and advancing green toxicology principles.

Metal Nanoparticles in Alzheimer's Disease

Nanotechnology has emerged in different fields of biomedical application, including lifestyle diseases like diabetes, hypertension, and chronic kidney disease, neurodegenerative diseases like Alzheimer's disease (AD), Parkinson's disease, and different types of cancers. Metal nanoparticles are one of the most used drug delivery systems due to the benefits of their enhanced physicochemical properties as compared to bulk metals. Neurodegenerative diseases are the second most cause affecting mortality worldwide after cancer. Hence, they require the most specific and targeted drug delivery systems for maximum therapeutic benefits. Metal nanoparticles are the preferred drug delivery system, possessing greater blood-brain barrier permeability, biocompatibility, and enhanced bioavailability. But some metal nanoparticles exhibit neurotoxic activity owing to their shape, size, surface charge, or surface modification. This review article has discussed the pathophysiology of AD. The neuroprotective mechanism of gold, silver, selenium, ruthenium, cerium oxide, zinc oxide, and iron oxide nanoparticles are discussed. Again, the neurotoxic mechanisms of gold, iron oxide, titanium dioxide, and cobalt oxide are also included. The neuroprotective and neurotoxic effects of nanoparticles targeted for treating AD are discussed elaborately. The review also focusses on the biocompatibility of metal nanoparticles for targeting the brain in treating AD. The clinical trials and the requirement to develop new drug delivery systems are critically analyzed. This review can show a path for the researchers involved in the brain-targeted drug delivery for AD.

Tetrahedral framework nucleic acid nanomaterials reduce the inflammatory damage in sepsis by inhibiting pyroptosis

Sepsis is a highly lethal condition and is caused by the dysregulation of the body's immune response to infection. Indeed, sepsis remains the leading cause of death in severely ill patients, and currently, no effective treatment is available. Pyroptosis, which is mainly activated by cytoplasmic danger signals and eventually promote the release of the pro-inflammatory factors, is a newly discovered programmed cell death procedure that clears infected cells while simultaneously triggering an inflammatory response. Increasing evidence indicates that pyroptosis participates in the development of sepsis. As a novel DNA nanomaterial, tetrahedral framework nucleic acids (tFNAs) characterized by its unique spatial structure, possess an excellent biosafety profile and can quickly enter the cell to impart anti-inflammatory and anti-oxidation effects. In this study, the roles of tFNAs in the in vitro model of macrophage cell pyroptosis and in the in vivo model of septic mice were examined, and it was found that tFNAs could mitigate organ inflammatory damage in septic mice, wherein they reduced inflammatory factor levels by inhibiting pyroptosis. These results provide possible new strategies for the future treatment of sepsis.

Immunotoxicity of Carbon-Based Nanomaterials, Starring Phagocytes

In the field of science, technology and medicine, carbon-based nanomaterials and nanoparticles (CNMs) are becoming attractive nanomaterials that are increasingly used. However, it is important to acknowledge the risk of nanotoxicity that comes with the widespread use of CNMs. CNMs can enter the body via inhalation, ingestion, intravenously or by any other route, spread through the bloodstream and penetrate tissues where (in both compartments) they interact with components of the immune system. Like invading pathogens, CNMs can be recognized by large numbers of receptors that are present on the surface of innate immune cells, notably monocytes and macrophages. Depending on the physicochemical properties of CNMs, i.e., shape, size, or adsorbed contamination, phagocytes try to engulf and process CNMs, which might induce pro/anti-inflammatory response or lead to modulation and disruption of basic immune activity. This review focuses on existing data on the immunotoxic potential of CNMs, particularly in professional phagocytes, as they play a central role in processing and eliminating foreign particles. The results of immunotoxic studies are also described in the context of the entry routes, impacts of contamination and means of possible elimination. Mechanisms of proinflammatory effect depending on endocytosis and intracellular distribution of CNMs are highlighted as well.

Nitric oxide-releasing biomaterials for promoting wound healing in impaired diabetic wounds: State of the art and recent trends

Impaired diabetic wounds are serious pathophysiological complications associated with persistent microbial infections including failure in the closure of wounds, and the cause of a high frequency of lower limb amputations. The healing of diabetic wounds is attenuated due to the lack of secretion of growth factors, prolonged inflammation, and/or inhibition of angiogenic activity. Diabetic wound healing can be enhanced by supplying nitric oxide (NO) endogenously or exogenously. NO produced inside the cells by endothelial nitric oxide synthase (eNOS) naturally aids wound healing through its beneficial vasculogenic effects. However, during hyperglycemia, the activity of eNOS is affected, and thus there becomes an utmost need for the topical supply of NO from exogenous sources. Thus, NO-donors that can release NO are loaded into wound healing patches or wound coverage matrices to treat diabetic wounds. The burst release of NO from its donors is prevented by encapsulating them in polymeric hydrogels or nanoparticles for supplying NO for an extended duration of time to the diabetic wounds. In this article, we review the etiology of diabetic wounds, wound healing strategies, and the role of NO in the wound healing process. We further discuss the challenges faced in translating NO-donors as a clinically viable nanomedicine strategy for the treatment of diabetic wounds with a focus on the use of biomaterials for the encapsulation and in vivo controlled delivery of NO-donors.

Gold Nanoparticles Green-Synthesized by the Suaeda japonica Leaf Extract and Screening of Anti-Inflammatory Activities on RAW 267.4 Macrophages

Biosynthesis of gold nanoparticles from medicinal plants has become a modern strategy in biomedical research based on their exclusive properties, including specific targeting, lower toxicity, and biocompatibility. In this study, gold nanoparticles, reduced by the Suaeda japonica leaf extract, were promptly validated by UV–visible (UV–Vis) spectroscopy at 548 nm. No additional reducing agents were needed in this kind of a reduction reaction, which provided evidence of green synthesis. Dynamic light scattering (DLS), energy-dispersive X-ray spectroscopy (EDX), field-emission transmission electron microscopy (FE-TEM), selected area electron diffraction (SAED), and X-ray diffraction (XRD) analyses were used to illustrate the nanoscale characterization of S. japonica gold nanoparticles (Sj-AuNps). Furthermore, the cytotoxicity effect of Sj-AuNps against the RAW 264.7 cell line was determined by performing an MTT assay. We also investigated Sj-AuNps’ anti-inflammatory properties in LPS-induced murine macrophages. These nanoparticles reduced the generation of nitric oxide (NO) and prostaglandin E2 (PGE2) and repressed the expression of the LPS-stimulated inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) genes. This study presents a significant biomedical application of S. japonica AuNps. The anti-inflammatory capabilities of Sj-AuNps underline their potential as possible options for suppressing inflammation-mediated diseases.

The Immune-Enhancing Properties of Hwanglyeonhaedok-Tang-Mediated Biosynthesized Gold Nanoparticles in Macrophages and Splenocytes

Background

Despite great advances in the field of immunotherapy, there is still a need for novel and effective immunostimulants to overcome challenges, such as instability and autoinflammatory toxicity, associated with conventional immunostimulants. Nanotechnology provides the possibility to overcome these challenges. The well-known classical Chinese formula, Hwanglyeonhaedok-tang (HHT) has been widely used to treat immune-related diseases in clinical practice.

Methods

We developed novel gold nanoparticles (AuNPs) utilizing one-pot synthesis with the herbal formula-HHT. The optimal conditions for HHT-AuNP biosynthesis were established, and physicochemical properties of the optimized HHT-AuNPs were identified using various spectrometric and microscopic techniques. Bio-TEM analysis revealed that HHT-AuNPs were highly engulfed within RAW264.7 cells without inducing cytotoxicity. The effect of HHT-AuNPs on immunostimulatory activity was evaluated in innate and adaptive immune cells (RAW264.7 macrophages and ICR mice splenocytes) using qRT-PCR, immunoblotting, and ELISA.

Results

The HHT-AuNPs remarkably increased the nitric oxide (NO) and immune-related cytokines production by activating the mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathways in RAW264.7 cells. Furthermore, HHT-AuNPs exerted immunostimulatory effects on mouse splenocytes by priming T/B-cells and macrophages.

Discussion

The present study is the first to demonstrate that HHT-AuNPs could be utilized as immunostimulators to activate both innate and adaptive immune systems. These results provide a foundation for the application of traditional Chinese medicinal formulae in the field of nanomedicine.

Gold Nanoparticles; Potential Nanotheranostic Agent in Breast Cancer: A Comprehensive Review with Systematic Search Strategy

BACKGROUND

Breast cancer is a heterogeneous disease typically prevalent among women and is the second-largest cause of death worldwide. Early diagnosis is the key to minimize the cancer-induced complication, however, the conventional diagnostic strategies have been sluggish, complex, and, to some extent, non-specific. Therapeutic tools are not so convenient and side effects of current therapies offer the development of novel theranostic tool to combat this deadly disease.

OBJECTIVE

This article aims to summarize the advances in the diagnosis and treatment of breast cancer with gold nanoparticles (GNP or AuNP).

METHODS

A systematic search was conducted in the three popular electronic online databases including PubMed, Google Scholar, and Web of Science, regarding GNP as breast cancer theranostics.

RESULTS

Published literature demonstrated that GNPs tuned with photosensitive moieties, nanomaterials, drugs, peptides, nucleotide, peptides, antibodies, aptamer, and other biomolecules improve the conventional diagnostic and therapeutic strategies of breast cancer management with minimum cytotoxic effect. GNP derived diagnosis system assures reproducibility, reliability, and accuracy cost-effectively. Additionally, surface-modified GNP displayed theranostic potential even in the metastatic stage of breast cancer.

CONCLUSION

Divergent strategies have shown the theranostic potential of surface tuned GNPs against breast cancer even in the metastatic stage with minimum cytotoxic effects both in vitro and in vivo.

Heterocellular spheroids of the neurovascular blood-brain barrier as a platform for personalized nanoneuromedicine

Nanoneuromedicine investigates nanotechnology to target the brain and treat neurological diseases. In this work, we biofabricated heterocellular spheroids comprising human brain microvascular endothelial cells, brain vascular pericytes and astrocytes combined with primary cortical neurons and microglia isolated from neonate rats. The structure and function are characterized by confocal laser scanning and light sheet fluorescence microscopy, electron microscopy, western blotting, and RNA sequencing. The spheroid bulk is formed by neural cells and microglia and the surface by endothelial cells and they upregulate key structural and functional proteins of the blood-brain barrier. These cellular constructs are utilized to preliminary screen the permeability of polymeric, metallic, and ceramic nanoparticles (NPs). Findings reveal that penetration and distribution patterns depend on the NP type and that microglia would play a key role in this pathway, highlighting the promise of this platform to investigate the interaction of different nanomaterials with the central nervous system in nanomedicine, nanosafety and nanotoxicology.

Superparamagnetic iron oxide nanoparticles attenuate lipopolysaccharide-induced inflammatory responses through modulation of toll-like receptor 4 expression

Superparamagnetic iron oxide nanoparticles (SPIONs) are extensively applied in biomedical fields, such as magnetic resonance imaging and as nanocarriers. However, the biosafety of SPIONs is not completely established, especially their effect on the immune system and inflammatory responses. Toll-like receptor (TLR) signaling is essential for many acute and chronic human inflammatory diseases. Regulation of TLR responses with drugs is helpful for these inflammatory conditions. In this study, we investigated the effects of 10 and 30 nm SPIONs on macrophages in the presence or absence of the TLR4 agonist lipopolysaccharide (LPS). We found that SPIONs inhibited the release of inflammatory cytokines induced by LPS both in murine and human macrophages in a concentration-dependent manner. Meanwhile, SPIONs suppressed inducible nitric oxide synthase expression activated by SPIONs in RAW264.7 macrophages. Additionally, TLR4 mRNA transcription and expression were attenuated with SPIONs treatment, which positively correlated with the release of inflammatory cytokines. In summary, our study demonstrates that SPIONs can suppress inflammatory responses, and the underlying mechanism may be regulated by TLR4 expression. Our present work contributes to clarifying the biosafety of SPIONs and provides a potential approach to alleviate human inflammatory diseases.

Metal nanomaterials: Immune effects and implications of physicochemical properties on sensitization, elicitation, and exacerbation of allergic disease

The recent surge in incorporation of metallic and metal oxide nanomaterials into consumer products and their corresponding use in occupational settings have raised concerns over the potential for metals to induce size-specific adverse toxicological effects. Although nano-metals have been shown to induce greater lung injury and inflammation than their larger metal counterparts, their size-related effects on the immune system and allergic disease remain largely unknown. This knowledge gap is particularly concerning since metals are historically recognized as common inducers of allergic contact dermatitis, occupational asthma, and allergic adjuvancy. The investigation into the potential for adverse immune effects following exposure to metal nanomaterials is becoming an area of scientific interest since these characteristically lightweight materials are easily aerosolized and inhaled, and their small size may allow for penetration of the skin, which may promote unique size-specific immune effects with implications for allergic disease. Additionally, alterations in physicochemical properties of metals in the nano-scale greatly influence their interactions with components of biological systems, potentially leading to implications for inducing or exacerbating allergic disease. Although some research has been directed toward addressing these concerns, many aspects of metal nanomaterial-induced immune effects remain unclear. Overall, more scientific knowledge exists in regards to the potential for metal nanomaterials to exacerbate allergic disease than to their potential to induce allergic disease. Furthermore, effects of metal nanomaterial exposure on respiratory allergy have been more thoroughly-characterized than their potential influence on dermal allergy. Current knowledge regarding metal nanomaterials and their potential to induce/exacerbate dermal and respiratory allergy are summarized in this review. In addition, an examination of several remaining knowledge gaps and considerations for future studies is provided.

Accelerated Bone Regeneration by Gold-Nanoparticle-Loaded Mesoporous Silica through Stimulating Immunomodulation

Bone repair and regeneration are greatly influenced by the local immune microenvironment. In this regard, the immunomodulatory capability of biomaterials should be considered when evaluating their osteogenic effects. In this study, we investigated the modulatory effects of gold nanoparticle (AuNP)-loaded mesoporous silica nanoparticles (Au-MSNs) on macrophages and the subsequent effects on the behavior of osteoblastic lineage cells. The results demonstrate that Au-MSNs could generate a favorable immune microenvironment by stimulating an anti-inflammatory response and promoting the secretion of osteogenic cytokines by macrophages. As a result, there is an enhancement of osteogenic differentiation in preosteoblastic MC3T3 cells as assessed by the increased expression of osteogenic markers, alkaline phosphatase (ALP) production, and calcium deposition. The immunomodulatory effects and direct osteogenic stimulation by Au-MSNs synergistically increased the osteogenic differentiation capability of MC3T3 cells as a result of crosstalk between Au-MSN-conditioned macrophages and Au-MSN-treated osteoblasts in a coculture system. An in vivo study further revealed that Au-MSNs could accelerate new bone formation in a critical-sized cranial defect site in rats based on computed tomography analysis and histological examination. Together, this novel Au-MSNs could significantly promote osteogenic activity by modulating the immune microenvironment, showing its therapeutic potential for bone tissue repair and regeneration.

Platinum Nanoparticles As A Therapeutic Agent Against Dextran Sodium Sulfate-Induced Colitis In Mice

PURPOSE

This study aimed to evaluate the anti-colitis potential of platinum nanoparticles (PtNPs).

MATERIALS AND METHODS

5-, 30- and 70-nm PtNPs were administered to C57BL/6 mice once daily by intragastric gavage for 8 d during and after 5-d dextran sodium sulfate treatment.

RESULTS

According to body weight change, stool blood and consistency, and colon length and histopathology, PtNPs size-dependently alleviated DSS-induced murine colitis. PtNPs enhanced gut-barrier function by upregulating the colonic expressions of heat-shock protein 25 and tight junction proteins. Based on colonic myeloperoxidase activity, colonic and peripheral levels of interleukin-6 and tumor necrosis factor-α, and peripheral counts of white blood cells, PtNPs attenuated colonic and systemic inflammation. By suppressing lipopolysaccharide-triggered production of proinflammatory mediators, including nitric oxide, tumor necrosis factor-α and interleukin-6, PtNPs exerted direct anti-inflammatory activities in RAW264.7 macrophages through a mechanism involving intracellular reactive oxygen species scavenging and Toll-like receptor 4/NF-κB signaling suppression. High-throughput 16S rRNA sequencing of fecal samples unveiled that PtNPs induced gut dysbiosis by unfavorably altering α-diversity, Firmicutes/Bacteroidetes ratio, and richness of certain specific bacteria.

CONCLUSION

PtNPs are a promising anti-colitis agent, but may negatively impact gut-microbiota.

Inhibition of inflammatory response in human keratinocytes by magnetic nanoparticles functionalized with PBP10 peptide derived from the PIP2-binding site of human plasma gelsolin

Background

Human plasma gelsolin (pGSN) is a multifunctional actin-binding protein involved in a variety of biological processes, including neutralization of pro-inflammatory molecules such as lipopolysaccharide (LPS) and lipoteichoic acid (LTA) and modulation of host inflammatory response. It was found that PBP10, a synthetic rhodamine B-conjugated peptide, based on the phosphoinositide-binding site of pGSN, exerts bactericidal activity against Gram-positive and Gram-negative bacteria, interacts specifically with LPS and LTA, and limits microbial-induced inflammatory effects. The therapeutic efficiency of PBP10 when immobilized on the surface of iron oxide-based magnetic nanoparticles was not evaluated, to date.

Results

Using the human keratinocyte cell line HaCaT stimulated by bacterially-derived LPS and LTA as an in vitro model of bacterial infection, we examined the anti-inflammatory effects of nanosystems consisting of iron oxide-based magnetic nanoparticles with aminosilane (MNP@NH₂) or gold shells (MNP@Au) functionalized by a set of peptides, derived from the phosphatidylinositol 4,5-bisphosphate (PIP2)-binding site of the human plasma protein gelsolin, which also binds LPS and LTA. Our results indicate that these nanosystems can kill both Gram-positive and Gram-negative bacteria and limit the production of inflammatory mediators, including nitric oxide (NO), reactive oxygen species (ROS), and interleukin-8 (IL-8) in the response to heat-killed microbes or extracted bacterial cell wall components. The nanoparticles possess the potential to improve therapeutic efficacy and are characterized by lower toxicity and improved hemocompatibility when compared to free peptides. Atomic force microscopy (AFM) showed that these PBP10-based nanosystems prevented changes in nanomechanical properties of cells that were otherwise stimulated by LPS.

Conclusions

Neutralization of endotoxemia-mediated cellular effects by gelsolin-derived peptides and PBP10-containing nanosystems might be considered as potent therapeutic agents in the improved therapy of bacterial infections and microbial-induced inflammation.

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.

Discovery of a sugar-based nanoparticle universally existing in boiling herbal water extracts and their immunostimulant effect

Herbal medicine is mainly prepared from boiling herbal water extracts. Many epoch-making immunosuppressant drugs, such as glycyrrhizic acid (old example) and FTY720 (current example), were developed from herbal secondary metabolites in the boiling water extract by partition with organic solvents. However, few immunostimulants have been discovered by this method. Instead of the usual method, we aimed to find a novel immunostimulant component by two unique methods in the research of herbal medicine: ultracentrifugation and electron microscopy. The immunostimulant was not a secondary metabolite, as expected, but the structure was a nanoparticle formed by a polysaccharide. In addition, we clarified the immune effect of the nanoparticle. Intake of the nanoparticle by phagocytosis resulted in immunostimulant effects by increasing the genes and proteins of inflammatory cytokines in macrophage cells. The immunostimulant effects were inhibited by a phagocytosis inhibitor, cytochalasin D. To the best of our knowledge, this study is the first to describe the discovery of a nanoparticle in boiling herbal water extracts and its immunostimulant properties. This study will provide additional understanding of the efficacy of herbal medicine, in that the immunostimulant nanoparticle universally exists in boiling herbal water extracts. Thus, traditional herbal medicine may be an oldest known nanomedicine. Furthermore, this study suggests that the immunostimulant nanoparticle simply can be obtained from herbal medicine only by ultracentrifugation. We hope that this simple strategy will substantially contribute to drug development, including vaccine adjuvant, in the future.

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Nanoparticles are universally present in boiling herbal water extracts.

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Nanoparticles are obtained from these extracts by ultracentrifugation.

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Nanoparticles are mainly composed of polysaccharides.

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Nanoparticles have an immunostimulatory effect on macrophage cells.

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This effect is exhibited by the phagocytosis of exogenous nanoparticles.

Peroxidase-Mimicking Nanoassembly Mitigates Lipopolysaccharide-Induced Endotoxemia and Cognitive Damage in the Brain by Impeding Inflammatory Signaling in Macrophages

Oxidative stress during sepsis pathogenesis remains the most-important factor creating imbalance and dysregulation in immune-cell function, usually observed following initial infection. Hydrogen peroxide (H₂O₂), a potentially toxic reactive oxygen species (ROS), is excessively produced by pro-inflammatory immune cells during the initial phases of sepsis and plays a dominant role in regulating the pathways associated with systemic inflammatory immune activation. In the present study, we constructed a peroxide scavenger mannosylated polymeric albumin manganese dioxide (mSPAM) nanoassembly to catalyze the decomposition of H₂O₂ responsible for the hyper-activation of pro-inflammatory immune cells. In a detailed manner, we investigated the role of mSPAM nanoassembly in modulating the expression and secretion of pro-inflammatory markers elevated in bacterial lipopolysaccharide (LPS)-mediated endotoxemia during sepsis. Through a facile one-step solution-phase approach, hydrophilic bovine serum albumin reduced manganese dioxide (BM) nanoparticles were synthesized and subsequently self-assembled with cationic mannosylated disulfide cross-linked polyethylenimine (mSP) to formulate mSPAM nanoassembly. In particular, we observed that the highly stable mSPAM nanoassembly suppressed HIF1α expression by scavenging H₂O₂ in LPS-induced macrophage cells. Initial investigation revealed that a significant reduction of free radicals by the treatment of mSPAM nanoassembly has reduced the infiltration of neutrophils and other leukocytes in a local endotoxemia animal model. Furthermore, therapeutic studies in a systemic endotoxemia model demonstrated that mSPAM treatment reduced TNF-α and IL-6 inflammatory cytokines in serum, in turn circumventing organ damage done by the inflammatory macrophages. Interestingly, we also observed that the reduction of these inflammatory cytokines by mSPAM nanoassembly further prevented IBA-1 immuno-positive microglial cell activation in the brain and consequently improved the cognitive function of the animals. Altogether, the administration of mSPAM nanoassembly scavenged H₂O₂ and suppressed HIF1α expression in LPS-stimulated macrophages and thereby inhibited the progression of local and systemic inflammation as well as neuroinflammation in an LPS-induced endotoxemia model. This mSPAM nanoassembly system could serve as a potent anti-inflammatory agent, and we further anticipate its successful application in treating various inflammation-related diseases.

Biogenic Polyphosphate Nanoparticles from a Marine Cyanobacterium Synechococcus sp. PCC 7002: Production, Characterization, and Anti-Inflammatory Properties In Vitro

Probiotic-derived polyphosphates have attracted interest as potential therapeutic agents to improve intestinal health. The current study discovered the intracellular accumulation of polyphosphates in a marine cyanobacterium Synechococcus sp. PCC 7002 as nano-sized granules. The maximum accumulation of polyphosphates in Synechococcus sp. PCC 7002 was found at the late logarithmic growth phase when the medium contained 0.74 mM of KH₂PO₄, 11.76 mM of NaNO₃, and 30.42 mM of Na₂SO₄. Biogenic polyphosphate nanoparticles (BPNPs) were obtained intact from the algae cells by hot water extraction, and were purified to remove the organic impurities by Sephadex G-100 gel filtration. By using 100 kDa ultrafiltration, BPNPs were fractionated into the larger and smaller populations with diameters ranging between 30–70 nm and 10–30 nm, respectively. 4′,6-diamidino-2-phenylindole fluorescence and orthophosphate production revealed that a minor portion of BPNPs (about 14–18%) were degraded during simulated gastrointestinal digestion. In vitro studies using lipopolysaccharide-activated RAW264.7 cells showed that BPNPs inhibited cyclooxygenase-2, inducible nitric oxide (NO) synthase expression, and the production of proinflammatory mediators, including NO, tumor necrosis factor-α, interleukin-6, and interleukin-1β through suppressing the Toll-like receptor 4/NF-κB signaling pathway. Overall, there is promise in the use of the marine cyanobacterium Synechococcus sp. PCC 7002 to produce BPNPs, an anti-inflammatory postbiotic.

In vitro toxicity studies of biodegradable, polyelectrolyte nanocapsules

Background

Toxicity of nanomaterials is one of the most important factors limiting their medical application. Evaluation of in vitro nanotoxicity allows for the identification and elimination of most of the toxic materials prior to animal testing. The current knowledge of the possible side effects of biodegradable nanomaterials, such as liposomes and polymeric organic nanoparticles, is limited. Previously, we developed a potential drug delivery system in the form of nanocapsules with polyelectrolyte, biodegradable shells consisting of poly-l-lysine and poly-l-glutamic acid (PGA), formed by the layer-by-layer adsorption technique.

Methods

Hemolysis assay, viability tests, flow cytometry analysis of vascular cell adhesion molecule-1 expression on endothelium, analysis of nitric oxide production, measurement of intracellular reactive oxygen species levels, detection of antioxidant enzyme activity, and analysis of DNA damage with comet assay were performed to study the in vitro toxicity of nanocapsules.

Results

In this work, we present the results of an in vitro analysis of toxicity of five-layer positively charged poly-l-lysine–terminated nanocapsules (NC5), six-layer negatively charged PGA-terminated nanocapsules (NC6) and five-layer PEGylated nanocapsules (NC5-PEG). PGA and polyethylene glycol (PEG) were used as two different “stealth” polymers. Of all the polyelectrolyte nanocapsules tested for blood compatibility, only cationic NC5 showed acute toxicity toward blood cells, expressed as hemolysis and aggregation. Neither NC6 nor NC5-PEG had proinflammatory activity evaluated through changes in the expression of NF-κB–dependent genes, iNOS and vascular cell adhesion molecule-1, induced oxidative stress, or promoted DNA damage in various cells.

Conclusion

Our studies clearly indicate that PGA-coated (negatively charged) and PEGylated polyelectrolyte nanocapsules do not show in vitro toxicity, and their potential as a drug delivery system may be safely studied in vivo.

Iron oxide nanoparticles enhance Toll-like receptor-induced cytokines in a particle size- and actin-dependent manner in human blood

Aim: To assess the effects of different-sized iron oxide nanoparticles (IONPs) on inflammatory responses in human whole blood. Materials & methods: Human whole blood with and without 10 and 30 nm IONPs was incubated with Toll-like receptor (TLR) ligands. Cytokine levels, complement activation, reactive oxygen species and viability were determined. Results: The 10 nm IONPs enhanced the TLR2/6, TLR4 and partly TLR8-mediated cytokine production, whereas the 30 nm IONPs partly enhanced TLR2/6 and decreased TLR8-mediated cytokine production. Particle-mediated enhancement of TLR4-induced cytokines could not be explained by complement activation, but was dependent on TLR4/MD2 and CD14, as well as actin polymerization. Conclusion: The IONPs differentially affected the TLR ligand-induced cytokines, which has important implications for biomedical applications of IONPs.

Gold nanoparticles induce serum amyloid A 1-Toll-like receptor 2 mediated NF-kB signaling in lung cells in vitro

Gold nanoparticles (AuNPs) have emerging applications in biomedicine and the industry. Exposure to AuNPs has previously been shown to alter the transcriptional activity of nuclear factor kappa B (NF-kB), which is known to mediate physiological and pathological processes. This study seeks to provide mechanistic insights into AuNP-induced NF-kB activation in Small Airway Epithelial Cells (SAECs) in vitro. Increased NF-kB transcriptional activity (quantified by the luciferase reporter assay) was observed in AuNP-treated SAECs. Transcriptomic analysis revealed differential expression of 42 genes, which regulate functional processes that include cellular response to stimulus, chemicals and stress as well as immune response. Notably, the gene expression of serum amyloid A1 (SAA1), an acute phase protein and Toll-like receptor 2 (TLR2) were found to be up-regulated. As TLR2 is known to be a functional receptor of SAA1, a co-immunoprecipitation assay was performed. SAA1 was observed to be co-immunoprecipitated with the TLR2 protein and this protein-protein interaction was further supported by in silico computer based protein modeling. The present study suggests that AuNPs may potentially induce SAA1-TLR2-mediated NF-kB transcription factor activation in lung epithelial cells, highlighting that nano-bio interactions could result in biological effects that may affect cells.

Anti-inflammatory and Antioxidative Effects of Tetrahedral DNA Nanostructures via the Modulation of Macrophage Responses

Tetrahedral DNA nanostructures (TDNs) are a new type of nanomaterials that have recently attracted attention in the field of biomedicine. However, the practical application of nanomaterials is often limited owing to the host immune response. Here, the response of RAW264.7 macrophages to TDNs was comprehensively evaluated. The results showed that TDNs had no observable cytotoxicity and could induce polarization of RAW264.7 cells to the M1 type. TDNs attenuated the expression of NO IL-1β (interleukin-1β), IL-6 (interleukin-6), and TNF-α (tumor necrosis factor-α) in LPS-induced RAW264.7 cells by inhibiting MAPK phosphorylation. In addition, TDNs inhibited LPS-induced reactive oxygen species (ROS) production and cell apoptosis by up-regulating the mRNA expression of antioxidative enzyme heme oxygenase-1 (HO-1). The findings of this study demonstrated that TDNs have great potential as a novel theranostic agent because of their anti-inflammatory and antioxidant activities, high bioavailability, and ease of targeting.

Molecular and immunological toxic effects of nanoparticles

Nanoparticles have emerged as a boon for the public health applications such as drug delivery, diagnostic, and imaging. Biodegradable and non-bio degradable nanoparticles have been used at a large scale level to increase the efficiency of the biomedical process at the cellular, animal and human level. Exponential use of nanoparticles reinforces the adverse immunological changes at the human health level. Physical and chemical properties of nanoparticles often lead to a variety of immunotoxic effects such as activation of stress-related genes, membrane disruption, and release of pro-inflammatory cytokines. Delivered nanoparticles in animal or human interact with various components of the immune system such as lymphocytes, macrophages, neutrophils etc. Nanoparticles delivered above the threshold level damages the cellular physiology by the generation of reactive oxygen and nitrogen species. This review article represents the potential of nanoparticles in the field of nanomedicine and provides the critical evidence which leads to develop immunotoxicity in living cells and organisms by altering immunological responses.

Lipopolysaccharide Adsorbed to the Bio-Corona of TiO2 Nanoparticles Powerfully Activates Selected Pro-inflammatory Transduction Pathways

It is known that the adsorption of bioactive molecules provides engineered nanoparticles (NPs) with novel biological activities. However, the biological effects of the adsorbed molecules may also be modified by the interaction with NP. Bacterial lipopolysaccharide (LPS), a powerful pro-inflammatory compound, is a common environmental contaminant and is present in several body compartments such as the gut. We recently observed that the co-incubation of LPS with TiO₂ NPs markedly potentiates its pro-inflammatory effects on murine macrophages, suggesting that, when included in a NP bio-corona, LPS activity is enhanced. To distinguish the effects of adsorbed LPS from those of the free endotoxin, a pellet fraction, denominated P25/LPS, was isolated by centrifugation from a mixture of P25 TiO₂ NP (128 µg/ml) and LPS (10 ng/ml) in the presence of fetal bovine serum. Western blot analysis of the pellet eluate indicated that the P25/LPS fraction contained, besides proteins, also LPS, pointing to the presence of LPS-doped NP. The effects of adsorbed or free LPS were then compared in Raw264.7 murine macrophages. RT-PCR was used to evaluate the induction of cytokine genes, whereas active, phosphorylated isoforms of proteins involved in signaling pathways were assessed with western blot. At a nominal LPS concentration of 40 pg/ml, P25/LPS induced the expression of both NF-κB and IRF3-dependent cytokines at levels comparable with those observed with free LPS (10 ng/ml), although with different time courses. Moreover, compared to free LPS, P25/LPS caused a more sustained phosphorylation of p38 MAPK and a more prolonged induction of STAT1-dependent genes. Cytochalasin B partially inhibited the induction of Tnfa by P25/LPS, but not by free LPS, and suppressed the induction of IRF3-dependent genes by either P25/LPS or free LPS. These data suggest that, when included in the bio-corona of TiO₂ NP, LPS exhibits enhanced and time-shifted pro-inflammatory effects. Thus, in assessing the hazard of NP in real life, the enhanced effects of adsorbed bioactive molecules should be taken into account.

MRI-guided and ultrasound-triggered release of NO by advanced nanomedicine

Nitric oxide (NO) has been well identified as a specific free radical molecule possessing wide-ranging therapeutic effects. Targeted delivery and controlled release of NO are highly desired to realize precision gas therapy, but are still challenging owing to the non-targetability and uncontrollability of NO itself. Herein, we propose a new concept of MRI-guided and ultrasound-triggered gas release for precision gas therapy. Based on this concept, we develop a novel ultrasound-responsive BNN-type NO-releasing molecule (NORM) and an advanced rattle-type nano-carrier of superparamagnetic iron oxide-encapsulated mesoporous silica nanoparticles (SPION@hMSN), and use them to construct a new intelligent nanomedicine (BNN6-SPION@hMSN) for the first time. The BNN6-SPION@hMSN nanomedicine exhibits excellent passive tumor-targeting capability, high MRI-guided tumor localization performance and a unique ultrasound-triggered NO release profile. The tumor-targeted, MRI-guided and ultrasound-triggered release profiles of the developed nanomedicine enable the tumor site-specific controlled release of NO in favor of high-efficacy and safe NO gas therapy of tumor.

Immunological properties of gold nanoparticles

In the past decade, gold nanoparticles have attracted strong interest from the nanobiotechnological community owing to the significant progress made in robust and easy-to-make synthesis technologies, in surface functionalization, and in promising biomedical applications. These include bioimaging, gene diagnostics, analytical sensing, photothermal treatment of tumors, and targeted delivery of various biomolecular and chemical cargos. For the last-named application, gold nanoparticles should be properly fabricated to deliver the cargo into the targeted cells through effective endocytosis. In this review, we discuss recent progress in understanding the selective penetration of gold nanoparticles into immune cells. The interaction of gold nanoparticles with immune cell receptors is discussed. As distinct from other published reviews, we present a summary of the immunological properties of gold nanoparticles. This review also summarizes what is known about the application of gold nanoparticles as an antigen carrier and adjuvant in immunization for the preparation of antibodies in vivo. For each of the above topics, the basic principles, recent advances, and current challenges are discussed. Thus, this review presents a detailed analysis of data on interaction of gold nanoparticles with immune cells. Emphasis is placed on the systematization of data over production of antibodies by using gold nanoparticles and adjuvant properties of gold nanoparticles. Specifically, we start our discussion with current data on interaction of various gold nanoparticles with immune cells. The next section describes existing technologies to improve production of antibodies in vivo by using gold nanoparticles conjugated with specific ligands. Finally, we describe what is known about adjuvant properties of bare gold or functionalized nanoparticles. In the Conclusion section, we present a short summary of reported data and some challenges and perspectives.

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.

One low-dose exposure of gold nanoparticles induces long-term changes in human cells

We report the in vitro long-term (20 wk) changes in cells exposed to well-characterized gold nanoparticles (Au NPs) with varying shapes and surface coatings under both chronic (exposure to Au NPs continuously over 20 wk) and nonchronic (initial acute cell exposure to Au NPs, followed by 20 wk in NP-free cell media) conditions. Both chronic and nonchronic Au NPs exposures at low dose induce modifications at the gene level after long periods. In attempt to overcome from the injuries caused by nanoparticle exposure, genes related to oxidative stress, cell cycle regulation, and inflammation are among those presenting differential expression levels. Surprisingly, the nonchronic exposure induced more gene expression changes than its chronic counterpart and the stress effects caused by this type of exposure were sustained even after 20 wk without any additional NP exposure. NP surface chemistry played an important role in the alteration of gene regulation. Overall, our data suggest that (i) cells can adaptively respond to chronic, low-level NP insults; (ii) the cell stress response is not reversible over time upon removal of NPs upon acute, nonchronic exposure; and (iii) polyethylene glycol is not as benign a surface chemistry as is generally supposed.

The effect of particle size on the genotoxicity of gold nanoparticles

Despite the increasing biomedical applications of gold nanoparticles (AuNPs), their toxicological effects need to be thoroughly understood. In the present study, the genotoxic potential of commercially available AuNPs with varying size (5, 20, and 50 nm) were assessed using a battery of in vitro and in vivo genotoxicity assays. In the comet assay, 20 and 50 nm AuNPs did not induce obvious DNA damage in HepG2 cells at the tested concentrations, whereas 5 nm NPs induced a dose-dependent increment in DNA damage after 24-h exposure. Furthermore, 5 nm AuNPs induced cell cycle arrest in G1 phase in response to DNA damage, and promoted the production of reactive oxygen species (ROS). In the chromosomal aberration test, AuNPs exposure did not increase in the frequency of chromosomal aberrations in Chinese hamster lung (CHL) cells. In the standard in vivo micronucleus test, no obvious increase in the frequency of micronucleus formation was found in mice after 4 day exposure of AuNPs. However, when the exposure period was extended to 14 days, 5 nm AuNPs presented significant clastogenic damage, with a dose-dependent increase of micronuclei frequencies. This finding suggests that particle size plays an important role in determining the genotoxicity of AuNPs. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 710-719, 2017.

Iron oxide nanoparticles modulate lipopolysaccharide-induced inflammatory responses in primary human monocytes

Co-stimulation of the immune system to more than one agent concomitantly is very common in real life, and considering the increasing use of engineered nanoparticles and nanomaterials, it is highly relevant to assess the ability of these materials to modulate key innate immune responses, which has not yet been studied in detail. We investigated the immunomodulatory effects of 10 nm and 30 nm iron oxide nanoparticles (IONPs) on primary human monocytes in the presence and absence of Toll-like receptor 4 agonist lipopolysaccharide (LPS). Prior to the cell studies, we characterized the physicochemical properties of the nanoparticles in cell culture medium and ensured that the nanoparticles were free from biological contamination. Cellular uptake of the IONPs in monocytes was assessed using transmission electron microscopy. Using enzyme-linked immunosorbent assay, we found that the IONPs per se did not induce the production of proinflammatory cytokines tumor necrosis factor-α, interleukin-6, and interleukin-1β. However, the IONPs had the ability to suppress LPS-induced nuclear factor kappa B activation and production of proinflammatory cytokines in primary human monocytes in an LPS and a particle dose-dependent manner. Using confocal microscopy and fluorescently labeled LPS, we showed that the effects correlated with impaired LPS internalization by monocytes in the presence of IONPs, which could be partly explained by LPS adsorption onto the nanoparticle surface. Additionally, the results from particle pretreatment experiments indicate that other cellular mechanisms might also play a role in the observed effects, which warrants further studies to elucidate the additional mechanisms underlying the capacity of IONPs to alter the reactivity of monocytes to LPS and to mount an appropriate cellular response.

Current understanding of interactions between nanoparticles and the immune system

The delivery of drugs, antigens, and imaging agents benefits from using nanotechnology-based carriers. The successful translation of nanoformulations to the clinic involves thorough assessment of their safety profiles, which, among other end-points, includes evaluation of immunotoxicity. The past decade of research focusing on nanoparticle interaction with the immune system has been fruitful in terms of understanding the basics of nanoparticle immunocompatibility, developing a bioanalytical infrastructure to screen for nanoparticle-mediated immune reactions, beginning to uncover the mechanisms of nanoparticle immunotoxicity, and utilizing current knowledge about the structure-activity relationship between nanoparticles' physicochemical properties and their effects on the immune system to guide safe drug delivery. In the present review, we focus on the most prominent pieces of the nanoparticle-immune system puzzle and discuss the achievements, disappointments, and lessons learned over the past 15years of research on the immunotoxicity of engineered nanomaterials.

Endotoxin contamination: a key element in the interpretation of nanosafety studies

The study of toxicity and potential risks of engineered nanoparticles is of particular importance in nanomedicine. Endotoxin, a common contaminant of bacterial origin, has biological effects that can mask the true biological effects of nanoparticles, if its presence is overlooked. In this review, we report the features of nanoparticle contamination by endotoxin, and the different biological effects of endotoxin-contaminated nanoparticles. We will describe different methods for endotoxin detection applied to nanoparticles, and discuss their pros and cons. Eventually, we describe various methods for eliminating endotoxin contamination in nanoparticles. Although there is no universal technique for efficiently removing endotoxin from nanoparticles, specific solutions can be found case by case, which can allow us to perform nanosafety studies in biologically relevant conditions.

A mitochondrial-targeting and NO-based anticancer nanosystem with enhanced photo-controllability and low dark-toxicity

Compared to the generation of singlet oxygen in photodynamic therapy, photo-generation of nitric oxide (NO) would not be limited by the concentration of molecular oxygen. However, therapeutic applications of exogenous nitric oxide are usually limited by its short half-life and its vulnerability to many biological substances, thus straightforward and precise control over NO delivery may be critical to its therapeutic effects. Herein, we demonstrate a mitochondrial-targeting and photoactive NO-releasing system as an anticancer drug. Fabricated by covalently incorporating a photo-responsive NO-donor and a mitochondrial targeting ligand onto carbon dots, this nanosystem exhibits a multi-functional nature which combines mitochondrial-targeting, photocontrollable NO-releasing and cell imaging. Upon cellular internalization, the nanosystem could target mitochondria effectively. Furthermore, the system displays little dark toxicity under physiological temperature; but upon light irradiation, it could release NO, efficiently damage mitochondria and consequently cause prominent apoptosis of cancer cells. Moreover, evaluated by using MTT assay, this nanosystem shows high cytotoxicity towards two cancer cell lines. These observations provide new insights for exploiting NO in disease therapy.

Selective inhibitory effects of 50-nm gold nanoparticles on mouse macrophage and spleen cells

Nanoparticles (NP) are significant to multiple industrial processes, consumer products and medical applications today. The health effects of many different types of NP, however, are largely unknown. The purpose of this study was to test the effects of 50-nm gold NP coated with poly-N-vinylpyrrolidone (PVP) on mouse macrophage and spleen cells with and without lipopolysaccharide (LPS), testing the hypothesis that the NP would modulate immune responses without being overtly toxic. Gold NP had no effect on macrophage viability and, in the absence of LPS, they had no effect on tumor necrosis factor (TNF)-α production as measured by ELISA. The presence of LPS significantly increased the release of TNFα from the macrophages above no-treatment controls, but increasing gold NP concentration led to decreasing release of TNFα. The reactive oxygen species (ROS) produced by exposed macrophages were also reduced compared to untreated controls, both with and without LPS, suggesting some kind of oxygen radical scavenging. In splenocyte cultures, gold NP had no effect alone, but significantly reduced the release of interleukin (IL)-17 and TNFα triggered by LPS. These results suggest that the gold NP used here are not cytotoxic to immune cells at these concentrations, but may affect cellular responses to infection or inflammation by altering the balance of cytokines.

Gold nanoparticles do not induce myotube cytotoxicity but increase the susceptibility to cell death

Gold nanoparticles (AuNP) have been widely used for many applications, including as biological carriers. A better understanding concerning AuNP safety on muscle cells is crucial, since it could be a potential tool in the nanomedicine field. Here, we describe the impact of polyethylene glycol-coated gold nanoparticles (PEG-AuNP) interaction with differentiated skeletal muscle C2C12 cells on cell viability, mitochondria function, cell signaling related to survival, cytokine levels and susceptibility to apoptosis. Intracellular localization of 4.5 nm PEG-AuNP diameter size was evidenced by STEM-in-SEM in myotube cells. Methods for cytotoxicity analysis showed that PEG-AuNP did not affect cell viability, but intracellular ATP levels and mitochondrial membrane potential increased. Phosphorylation of ERK was not altered but p-AKT levels reduced (p<0.01). Pre-treatment of cells with PEG-AuNP followed by staurosporine induction increased the caspases-3/7 activity. Indeed, cytokines analysis revealed a sharp increase of IFN-γ and TGF-β1 levels after PEG-AuNP treatment, suggesting that inflammatory and fibrotic phenotypes process were activated. These data demonstrate that PEG-AuNP affect the myotube physiology leading these cells to be more susceptible to death stimuli in the presence of staurosporine. Altogether, these results present evidence that PEG-AuNP affect the susceptibility to apoptosis of muscle cells, contributing to development of safer strategies for intramuscular delivery.

Titanium dioxide nanoparticles enhance macrophage activation by LPS through a TLR4-dependent intracellular pathway

TiO₂nanoparticles enhance LPS-dependent NO production and cytokine secretion through a mechanism that involves TLR4-mediated p38-signalling and requires phagocytosis.

Long-term effects of nanoparticles on nutrition and metabolism

Nanoparticles have shown great potential in biological and biomedical applications due to their distinct physical and chemical properties. In the meanwhile, the biosafety of nanoparticles has also raised intense concerns worldwide. To address such concerns, great efforts have been made to examine short-term effects of nanoparticles on cell survival and proliferation. More recently, exploration of long-term effects of nanomaterials, particularly those with promising biomedical applications in vivo, has aroused significant interest. For example, gold nanoparticles (AuNPs) are generally considered non-toxic to cell growth, whereas recent studies suggest that AuNPs might have long-term effects on cellular metabolism and energy homeostasis. In this Review, recent advances in this direction are summarized. Further, possible mechanisms under which nanoparticles regulate metabolic signaling pathways, potential long-term effects on cellular anabolic or catabolic processes, and their implications in human health and metabolic disorders are discussed.

The unexpected effect of PEGylated gold nanoparticles on the primary function of erythrocytes

Polyethylene glycol-functionalized gold nanoparticles (PEGylated AuNPs) have been widely used as nanocarriers for the delivery of various drugs. However, little attention has been paid to whether the PEGylated AuNPs could affect the primary function of human erythrocytes, which is the main cellular component in the blood. In the current study, we show that both the deformability and oxygen-delivering ability of erythrocytes are decreased when treated with PEGyalted AuNPs of various sizes, which can be attributed to the interaction between PEGylated AuNPs and erythrocyte membranes. It is observed that the PEGylated AuNPs could also induce the aggregation of band-3 and the ATP decrease of erythrocytes. In addition, the PEGylated AuNPs can accelerate the loss of CD47 on erythrocyte membranes, possibly enhancing the senescent process of erythrocytes and the following clearance by SIRPα-expressing leukocytes in bloodstream. The results suggested that PEGylated AuNPs have the potential to affect the primary function of human erythrocytes, which should be considered when using them as drug carriers.

Analysis of cellular responses of macrophages to zinc ions and zinc oxide nanoparticles: a combined targeted and proteomic approach

Two different zinc oxide nanoparticles, as well as zinc ions, are used to study the cellular responses of the RAW 264 macrophage cell line. A proteomic screen is used to provide a wide view of the molecular effects of zinc, and the most prominent results are cross-validated by targeted studies. Furthermore, the alteration of important macrophage functions (e.g. phagocytosis) by zinc is also investigated. The intracellular dissolution/uptake of zinc is also studied to further characterize zinc toxicity. Zinc oxide nanoparticles dissolve readily in the cells, leading to high intracellular zinc concentrations, mostly as protein-bound zinc. The proteomic screen reveals a rather weak response in the oxidative stress response pathway, but a strong response both in the central metabolism and in the proteasomal protein degradation pathway. Targeted experiments confirm that carbohydrate catabolism and proteasome are critical determinants of sensitivity to zinc, which also induces DNA damage. Conversely, glutathione levels and phagocytosis appear unaffected at moderately toxic zinc concentrations.

Saikosaponin A mediates the inflammatory response by inhibiting the MAPK and NF-κB pathways in LPS-stimulated RAW 264.7 cells

Saikosaponin A (SSA) is a major triterpenoid saponin isolated from Radix bupleuri (RB), a widely used Chinese traditional medicine to treat various inflammation-related diseases. The aim of this study was to investigate the anti-inflammatory activity, as well as the molecular mechanism of SSA in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. In this study, we demonstrated that SSA markedly inhibits the expression of certain immune-related cytotoxic factors, including cyclooxygenase-2 (COX-2) and inducible nitric-oxide synthase (iNOS), as well as pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6. It also significantly upregulates the expression of IL-10, an important anti-inflammatory cytokine, suggesting its anti-inflammatory activity in LPS-stimulated macrophages. We further demonstrated that SSA inhibits the activation of the nuclear factor-κB (NF-κB) signaling pathway by suppressing the phosphorylation of inhibitory NF-κB inhibitor α (IκBα) and thus holding p65 NF-κB in the cytoplasm to prevent its translocation to the nucleus. In addition, SSA also inhibits the mitogen-activated protein kinase (MAPK) signaling pathway by downregulating the phosphorylation of p38 MAPK, c-Jun N-terminal kinase (c-JNK) and extracellular signal-regulated kinase (ERK), the three key components of the MAPK family. In conclusion, our study demonstrates that SSA has an anti-inflammatory effect by regulating inflammatory mediators and suppressing the MAPK and NF-κB signaling pathways in LPS-stimulated RAW 264.7 cells.