In vivo quantification of quantum dot systemic transport in C57BL/6 hairless mice following skin application post-ultraviolet radiation

Immunomodulatory effects of nanoparticles on dendritic cells in a model of allergic contact dermatitis: importance of PD-L2 expression

Nanoparticle (NP) skin exposure is linked to an increased prevalence of allergic contact dermatitis. In our prior studies using the mouse contact hypersensitivity (CHS) model, we reported that silica 20 nm (SiO2) NPs suppressed the allergic response and titanium dioxide NPs doped with manganese (mTiO2) exacerbated it. In this work, we conducted in vitro experiments using bone marrow-derived dendritic cells (BMDCs) to study the combinatorial effect of the potent 2,4-dinitrofluorobenzene (DNFB) hapten sensitizer with SiO2 and mTiO2 NPs on BMDC cytotoxicity, cytokine secretion and phenotype using the B7 family ligands. Results show that DNFB and mTiO2 behave similarly and exhibit proinflammatory characteristics while SiO2 promotes a naive phenotype. We observe that the B7-H3 (CD276) ligand is only expressed on CD80 + (B7-1) BMDCs. Results from adoptive transfer CHS studies, combined with BMDC phenotype analysis, point to the importance of PD-L2 expression in modulating the adaptive immune response. This work identifies metrics that can be used to predict the effects of NPs on contact allergy and to guide efforts to engineer cell-based therapies to induce hapten specific immune tolerance.

Immunomodulatory Effects of Nanoparticles on Dendritic Cells in a Model of Allergic Contact Dermatitis - Importance of PD-L2 Expression

Nanoparticle (NP) skin exposure is linked to the increased prevalence of allergic contact dermatitis. In prior studies using the mouse contact hypersensitivity (CHS) model, we reported that silica 20 nm (Si20nm) suppressed the allergic response and TiO2 doped with manganese (mTiO2) exacerbated it. In this work, we conducted in vitro experiments using bone marrow-derived dendritic cells (BMDCs) to study the combinatorial effect of the potent 2, 4-dinitrofluorobenzene (DNFB) hapten sensitizer with Si20nm and mTiO2 NPs on BMDC cytotoxicity, cytokine secretion and phenotype using the B7 family ligands. Results show that DNFB and mTiO2 behave similarly and exhibit proinflammatory characteristics while Si20nm promotes a naive phenotype. We observe that the B7-H3 (CD276) ligand is only expressed on CD80+ (B7-1) BMDC. Results from adoptive transfer CHS studies, combined with BMDC phenotype analysis, point to the importance of PD-L2 expression in modulating the adaptive immune response. This work identifies metrics that can be used to predict the effects of NPs on contact allergy and to guide efforts to engineer cell-based therapies to induce antigen specific immune tolerance.

An update on the biological effects of quantum dots: From environmental fate to risk assessment based on multiple biological models

Quantum dots (QDs) are zero-dimension nanomaterials with excellent physical and chemical properties, which have been widely used in environmental science and biomedicine. Therefore, QDs are potential to cause toxicity to the environment and enter organisms through migration and bioenrichment effects. This review aims to provide a comprehensive and systematic analysis on the adverse effects of QDs in different organisms based on recently available data. Following PRISMA guidelines, this study searched PubMed database according to the pre-set keywords, and included 206 studies according to the inclusion and elimination criteria. CiteSpace software was firstly used to analyze the keywords of included literatures, search for breaking points of former studies, and summarize the classification, characterization and dosage of QDs. The environment fate of QDs in the ecosystems were then analyzed, followed with comprehensively summarized toxicity outcomes at individual, system, cell, subcellular and molecular levels. After migration and degradation in the environment, aquatic plants, bacteria, fungi as well as invertebrates and vertebrates have been found to be suffered from toxic effects caused by QDs. Aside from systemic effects, toxicity of intrinsic QDs targeting to specific organs, including respiratory system, cardiovascular system, hepatorenal system, nervous system and immune system were confirmed in multiple animal models. Moreover, QDs could be taken up by cells and disturb the organelles, which resulted in cellular inflammation and cell death, including autophagy, apoptosis, necrosis, pyroptosis and ferroptosis. Recently, several innovative technologies, like organoids have been applied in the risk assessment of QDs to promote the surgical interventions of preventing QDs' toxicity. This review not only aimed at updating the research progress on the biological effects of QDs from environmental fate to risk assessment, but also overcame the limitations of available reviews on basic toxicity of nanomaterials by interdisciplinarity and provided new insights for better applications of QDs.

An overview of quantum dots-induced immunotoxicity and the underlying mechanisms

Quantum dots (QDs) have bright luminescence and excellent photostability. New synthesis techniques and strategies also enhance QDs properties for specific applications. With the continuous expansion of the applications, QDs-mediated immunotoxicity has become a major concern. The immune system has been confirmed to be an important target organ of QDs and is sensitive to QDs. Herein, review immunotoxic effects caused by QDs and the underlying mechanisms. Firstly, QDs exposure-induced modulation in immune cell maturation and differentiation is summarized, especially pre-exposed dendritic cells (DCs) and their regulatory roles in adaptive immunity. Cytokines are usually recognized as biomarkers of immunotoxicity, therefore, variation of cytokines mediated by QDs is also highlighted. Moreover, the activation of the complement system induced by QDs is discussed. Accumulated results have suggested that QDs disrupt the immune response by regulating intracellular oxidative stress (reactive oxygen species) levels, autophagy formation, and expressions of pro-inflammatory mediators. Furthermore, several signalling pathways play a key role in the disruption. Finally, some difficulties worthy of further consideration are proposed. Because there are still challenges in biomedical and clinical applications, this review hopes to provide information that could be useful in exploring the mechanisms associated with QD-induced immunotoxicity.

A resveratrol-loaded nanostructured lipid carrier hydrogel to enhance the anti-UV irradiation and anti-oxidant efficacy

Exposure to ultraviolet (UV) irradiation leads to the generation of reactive oxygen species (ROS) and DNA damage in skin tissue, which can further result in skin cancers. Using sunscreens is one of the most popular and the most effective method to resist UV irradiation. Resveratrol (RES) shows high absorbance in UV region and significant anti-oxidant effects. However, RES is easily degraded by UV irradiation, resulting in the decrease of bioactivity and the limitation of its application in the pharmaceutical preparations of skin. In this paper, a nanostructured lipid carrier gel loaded with RES (RES-NLC-gel) was prepared to improve the stability of RES and the accumulation of RES in the epidermis. Moreover, RES-NLC-gel could scavenge free radical effectively and protect human keratinocyte from UV irradiation by inhibiting the generation of ROS, decreasing the protein expression of cleaved caspase-3 and Bax and increasing the protein expression of Bcl-2. When mice skin was pretreated with RES-NLC-gel, there were less erythema, wrinkles and scabs on mice skin. The epidermal thickness of mice skins obviously reduced in dose-dependent manner. The activities of catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD) in mice skin tissue significantly increased. Thus, RES-NLC-gel exhibited an obvious anti-UV irradiation and anti-oxidant activity in vivo. RES-NLC-gel displayed great application potential in protecting skin from UV irradiation.

Graphene Quantum Dots as Intracellular Imaging-Based Temperature Sensors

Non-invasive temperature sensing is necessary to analyze biological processes occurring in the human body, including cellular enzyme activity, protein expression, and ion regulation. To probe temperature-sensitive processes at the nanoscale, novel luminescence nanothermometers are developed based on graphene quantum dots (GQDs) synthesized via top-down (RGQDs) and bottom-up (N-GQDs) approaches from reduced graphene oxide and glucosamine precursors, respectively. Because of their small 3-6 nm size, non-invasive optical sensitivity to temperature change, and high biocompatibility, GQDs enable biologically safe sub-cellular resolution sensing. Both GQD types exhibit temperature-sensitive yet photostable fluorescence in the visible and near-infrared for RGQDs, utilized as a sensing mechanism in this work. Distinctive linear and reversible fluorescence quenching by up to 19.3% is observed for the visible and near-infrared GQD emission in aqueous suspension from 25 °C to 49 °C. A more pronounced trend is observed with GQD nanothermometers internalized into the cytoplasm of HeLa cells as they are tested in vitro from 25 °C to 45 °C with over 40% quenching response. Our findings suggest that the temperature-dependent fluorescence quenching of bottom-up and top-down-synthesized GQDs studied in this work can serve as non-invasive reversible/photostable deterministic mechanisms for temperature sensing in microscopic sub-cellular biological environments.

A review to support the derivation of a worst-case dermal penetration value for nanoparticles

Data on dermal penetration of nanoparticles (NPs) was reviewed with the goal to establish a worst-case dermal penetration value for NPs. To this aim, the main focus was on studies providing quantitative dermal penetration data (29 studies). In vivo dermal penetration studies and ex vivo studies based on skin explants were included. These studies used NPs with different compositions, dimensions, and shapes. The overall results showed that skin is an efficient barrier for NPs, indistinctly of their properties. However, some studies reported that a small percentage of the applied NP dose penetrated the skin surface and reached deeper skin layers. The integrity of the skin layer and the product formulation were more critical determinants of dermal penetration than the NP properties. Most quantitative studies were based on elemental analysis such that it cannot be concluded if detected levels are attributable to a dissolved fraction or to the penetration of particles as such. Results of qualitative imaging studies suggest that at least a fraction of the levels reported in quantitative studies could be due to particle penetration. Altogether, based on the data compiled, we propose that 1% could be used as a worst-case dermal penetration value for nanoparticles within the boundaries of the properties of those included in our analysis.

The UVR Filter Octinoxate Modulates Aryl Hydrocarbon Receptor Signaling in Keratinocytes via Inhibition of CYP1A1 and CYP1B1

Ultraviolet radiation (UVR) is a consistent part of the environment that has both beneficial and harmful effects on human health. UVR filters in the form of commercial sunscreens have been widely used to reduce the negative health effects of UVR exposure. Despite their benefit, literature suggests that some filters can penetrate skin and have off-target biological effects. We noted that many organic filters are hydrophobic and contain aromatic rings, making them potential modulators of Aryl hydrocarbon Receptor (AhR) signaling. We hypothesized that some filters may be able to act as agonists or antagonists on the AhR. Using a luciferase reporter cell line, we observed that the UVR filter octinoxate potentiated the ability of the known AhR ligand, 6-formylindolo[3,2-b]carbazole (FICZ), to activate the AhR. Cotreatments of keratinocytes with octinoxate and FICZ lead to increased levels of cytochrome P4501A1 (CYP1A1) and P4501B1 (CYP1B1) mRNA transcripts, in an AhR-dependent fashion. Mechanistic studies revealed that octinoxate is an inhibitor of CYP1A1 and CYP1B1, with IC50 values at approximately 1 µM and 586 nM, respectively. In vivo topical application of octinoxate and FICZ also elevated CYP1A1 and CYP1B1 mRNA levels in mouse skin. Our results show that octinoxate is able to indirectly modulate AhR signaling by inhibiting CYP1A1 and CYP1B1 enzyme function, which may have important downstream consequences for the metabolism of various compounds and skin integrity. It is important to continue studying the off-target effects of octinoxate and other UVR filters, because they are used on skin on a daily basis world-wide.

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.

Cytotoxicity of CdTe quantum dots with different surface coatings against yeast Saccharomyces cerevisiae

Cadmium (Cd)-based QDs are well studied owing to their excellent optical properties. The applications of Cd-based QDs in biomedical filed, however, is hindered by its inherent toxicity. In this study, to overcome the inherent toxicity of heavy metals, CdTe QDs were encapsulated with different shells (NAC, MPA and GSH) to reduce the leakage of Cd from the core. We studied the cytotoxicity of the three kinds of CdTe QDs on S. cerevisiae by spectroscopic, electrochemical, microscopic methods and microcalorimetric technique. Results showed that toxicity of CdTe QDs increased with the augment of QD concentration. According to the values of IC₅₀ ((GSH-CdTe QDs (15.3 nmol/L) < MPA-CdTe QDs (56.2 nmol/L) < NAC-CdTe QDs (89.8 nmol/L)), the most toxic one is GSH-CdTe QDs, followed by MPA-CdTe QDs, then NAC-CdTe QDs. The coatings have contribution to their toxicity. The three kinds of QDs with the similar shape (sphere) can enter the cell by the clathrin-mediated endocytosis and lead to the different impairments. The mechanism of cytotoxicity is due to the release of Cd²⁺ leading elevation of intracellular reactive oxygen species (ROS), which damage mitochondria. The clathrin-mediated endocytosis is a significant factor in determining the toxicity of CdTe QDs.

Amorphous silicon dioxide nanoparticles modulate immune responses in a model of allergic contact dermatitis

Amorphous silicon dioxide nanoparticles (SiNPs) are ubiquitous, and they are currently found in cosmetics, drugs, and foods. Biomedical research is also focused on using these nanoparticles as drug delivery and bio-sensing platforms. Due to the high potential for skin exposure to SiNPs, research into the effect of topical exposure on both healthy and inflammatory skin models is warranted. While we observe only minimal effects of SiNPs on healthy mouse skin, there is an immunomodulatory effect of these NPs in a model of allergic contact dermatitis. The effect appears to be mediated partly by keratinocytes and results in decreases in epidermal hyperplasia, inflammatory cytokine release, immune cell infiltration, and a subsequent reduction in skin swelling. Additional research is required to further our mechanistic understanding and to validate the extent of this immunomodulatory effect in human subjects in order to assess the potential prophylactic use of SiNPs for treating allergic skin conditions.

Verification of Long-Term Genetic Stability of hMSCs during Subculture after Internalization of Sunflower-Type Nanoparticles (SF-NPs)

Background: For many years, researchers have sought to overcome major challenges in the use of nanoparticles as therapeutics, including issues related to intracellular delivery, biocompatibility, and activation. In particular, the genetic stability of cells treated with nanoparticles has become increasingly important in the context of stem cell therapy. Methods: Functional nanoparticles (Sunflower typed nanoparticles; SF-NPs) were fabricated by coating heparin pluronic F127 gels with quantum dot nanoparticles (QDs), and then bound the SOX9 gene to the QD nanogels. The resultant nanoparticles were transferred into stem cells, and the effect on genetic stability was monitored. To determinate gene delivery efficacy and long-term genomic stability of cells transfected with QD nanogels, hMSCs were transfected with nanogels at passage 4 (T1; Transfected cells 1) and then sub-cultured to passage of (T4). Following transplantation of transfected T1-T4 cells, the cells were monitored by in vivo imaging. The genetic stability of cells treated with nanoparticles was confirmed by chromosomal analysis, copy number variation (CNV) analysis, and mRNA profiling. Results: After 21 days of pellet culture after sub-culture from T1 to T4, hMSCs treated with QD nanogels complexed with SOX9 plasmid DNA (pDNA) significantly increased expression of specific extracellular matrix (ECM) polysaccharides and glycoproteins, as determined by Safranin O and Alcian blue staining. Moreover, the T4 hMSCs expressed higher levels of specific proteins, including collagen type II (COLII) and SOX9, than P4 hMSCs, with no evidence of DNA damage or genomic malfunction. Microarray analysis confirmed expression of genes specific to matured chondrocytes. Stem cells that internalized nanoparticles at the early stage retained genetic stability, even after passage. In in vivo studies in rats, neuronal cartilage formation was observed in damaged lesions 6 weeks after transplantation of T1 and T4 cells. The degree of differentiation into chondrocytes in the cartilage defect area, as determined by mRNA and protein expression of COLII and SOX9, was higher in rats treated with SF-NPs. Conclusion: The QD nanogels used in this study, did not affect genome integrity during long-term subculture, and are thus suitable for multiple theranostic applications.

Prenatal alcohol exposure is a risk factor for adult neuropathic pain via aberrant neuroimmune function

BACKGROUND

Clinical studies show that prenatal alcohol exposure (PAE) results in effects that persist into adulthood. Experimental animal models of moderate PAE demonstrate that young adults with PAE display potentiated sensitivity to light touch, clinically termed allodynia, following sciatic nerve chronic constriction injury (CCI) that coincides with heightened spinal glial, spinal macrophage, and peripheral immune responses. However, basal touch sensitivity and corresponding glial and leukocyte activation are unaltered. Therefore, the current study explored whether the enduring pathological consequences of moderate PAE on sensory processing are unmasked only following secondary neural insult.

METHODS

In middle-aged (1 year) Long Evans rats that underwent either prenatal saccharin exposure (control) or moderate PAE, we modified the well-characterized model of sciatic neuropathy, CCI, to study the effects of PAE on neuro-immune responses in adult offspring. Standard CCI manipulation required 4 chromic gut sutures, while a mild version applied a single suture loosely ligated around one sciatic nerve. Spinal glial immunoreactivity was examined using immunohistochemistry. The characterization and functional responses of leukocyte populations were studied using flow cytometry and cell stimulation assays followed by quantification of the proinflammatory cytokines interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α). Data were statistically analyzed by ANOVA and unpaired t tests.

RESULTS

The current report demonstrates that mild CCI generates robust allodynia only in PAE rats, while the pathological effects of PAE following the application of a standard CCI are revealed by enhanced allodynia and elevated spinal glial activation. Additionally, mild CCI increases spinal astrocyte activation but not microglia, suggesting astrocytes play a larger role in PAE-induced susceptibility to aberrant sensory processing. Leukocyte populations from PAE are altered under basal conditions (i.e., prior to secondary insult), as the distribution of leukocyte populations in lymphoid organs and other regions are different from those of controls. Lastly, following in vitro leukocyte stimulation, only PAE augments the immune response to antigen stimulation as assessed by heightened production of TNF-α and IL-1β.

CONCLUSIONS

These studies demonstrate PAE may prime spinal astrocytes and peripheral leukocytes that contribute to enduring susceptibility to adult-onset neuropathic pain that is not apparent until a secondary insult later in life.