Sang Hoon Jeong

Effect of the size and surface charge of silica nanoparticles on cutaneous toxicity

Silica nanoparticles (NPs) are widely applied in many fields, such as chemical industry, medicine, cosmetics, and agriculture. However, the hazardous effects of silica NPs exposure are not completely understood. In this study, the two different sizes (20 nm and 100 nm) and different charges (negatively charged [NC] and weakly negatively charged [WNC]) of silica NPs were used. The present study investigated the cytotoxicity and reactive oxygen species (ROS) generation of silica NPs on keratinocytes. The phototoxicity test of silica NPs was performed on skin fibroblast cells. In addition, skin irritation and skin sensitization of silica NPs were studied on HSEM and mouse skin, respectively. The cell viability of NC 20 nm silica NPs was decreased. However, there are no cytotoxicity for NC 100 nm silica NPs and WNC silica NPs (20 and 100 nm). The results for silica NPs-induced ROS generation are consistent with the cytotoxicity test by silica NPs. Further, NC and WNC silica NPs induced no phototoxicity, acute cutaneous irritation, or skin sensitization. These results suggested that silica NPs-induced ROS generation was the determinant of cytotoxicity. This study showed that the smaller size (20 nm) of silica NPs had more toxicity than the larger size (100 nm) of silica NPs for NC silica NPs. Moreover, we observed an effect of surface charge in cytotoxicity and ROS generation, by showing that the NC silica NPs (20 nm) had more toxic than the WNC silica NPs (20 nm). These findings suggested that the surface charge of silica NPs might be the important parameter for silica NPs-induced toxicity. Further study is needed to assess the effect of surface modification of nanotoxicity.

Assessment of penetration of quantum dots through in vitro and in vivo human skin using the human skin equivalent model and the tape stripping method.

Quantum dots (QDs) are rapidly emerging as an important class of nanoparticles (NPs) with potential applications in medicine. However, little is known about penetration of QDs through human skin. This study investigated skin penetration of QDs in both in vivo and in vitro human skin. Using the tape stripping method, this study demonstrates for the first time that QDs can actually penetrate through the stratum corneum (SC) of human skin. Transmission electron microscope (TEM) and energy diverse X-ray (EDX) analysis showed accumulation of QDs in the SC of a human skin equivalent model (HSEM) after dermal exposure to QDs. These findings suggest possible transdermal absorption of QDs after dermal exposure over a relatively long period of time.

Assessment of dermal toxicity of nanosilica using cultured keratinocytes, a human skin equivalent model and an in vivo model.

Assessments of skin irritation potentials are important aspects of the development of nanotechnology. Nanosilica is currently being widely used for commercial purposes, but little literature is available on its skin toxicity and irritation potential. This study was designed to determine whether nanosilica has the potential to cause acute cutaneous toxicity, using cultured HaCaT keratinocytes (CHK), a human skin equivalent model (HSEM), and invivo model. Nanosilica was characterized by scanning electron microscopy. We evaluated the cytotoxic effects of nanosilica on CHKs and the HSEM. In addition, we also investigated whether two commercially available nanosilicas with different sizes (7 and 10-20 nm) have different effects. To confirm invitro results, we evaluated the irritation potentials of nanosilicas on rabbit skin. Nanosilicas reduced the cell viabilities of CHKs in a dose-dependent manner. However, the HSEM revealed no irritation at 500 microg/ml of nanosilica. Furthermore, this result concurred with Draize skin irritation test findings. The present study data indicate that nanosilica does not cause acute cutaneous irritation. Furthermore, this study shows that the HSEM used provides more useful screening data than the conventional cell culture model on the relative toxicities of NPs.

Analysis for the potential of polystyrene and TiO2 nanoparticles to induce skin irritation, phototoxicity, and sensitization.

The human skin equivalent model (HSEM) is well known as an attractive alternative model for evaluation of dermal toxicity. However, only limited data are available on the usefulness of a HSEM for nanotoxicity testing. This study was designed to investigate cutaneous toxicity of polystyrene and TiO2 nanoparticles using cultured keratinocytes, a HSEM, and an animal model. In addition, we also evaluated the skin sensitization potential of nanoparticles using a local lymph node assay with incorporation of BrdU. Findings from the present study indicate that polystyrene and TiO2 nanoparticles do not induce phototoxicity, acute cutaneous irritation, or skin sensitization. Results from evaluation of the HSEMs correspond well with those from animal models. Our findings suggest that the HSEM might be a useful alternative model for evaluation of dermal nanotoxicity.

ZnO nanoparticles induce TNF-α expression via ROS-ERK-Egr-1 pathway in human keratinocytes

BACKGROUND The area of nanotechnology continues to expand rapidly and zinc oxide (ZnO) nanoparticles (NPs) are widely being used in cosmetics and sunscreens. Although ZnO-NPs are considered materials that can potentially cause skin inflammation, the underlying mechanisms remain elusive. OBJECTIVE The aim of this study was to investigate the signaling pathways of a cutaneous inflammatory response induced by ZnO-NPs. ZnO-NPs increased the early growth response-1 (Egr-1) expression, promoter activity and its nuclear translocation in HaCaT cells. METHODS HaCaT cells and primary keratinocytes were exposed to ZnO NPs over a range of doses and time course. Protein levels and mRNA levels of Egr-1 and mitogen-activated protein kinase (MAPK) were measured by Western blot and ELISA, respectively. As an in vivo study, ZnO-NPs were applicated on mouse skin, and immunohistochemical stain with TNF-α and Egr-1 was done. RESULTS ZnO-NPs activated extracellular signal-regulated kinase (ERK) of MAPK pathways. The up-regulation of Egr-1 expression by ZnO-NPs stimulation was found to be inhibited by an ERK inhibitor, but by neither c-Jun-N-terminal kinase (JNK) nor p38 inhibitor. Antioxidative N-acetyl-cysteine (NAC) strongly inhibited the level of Egr-1 and phosphorylated ERK expression in ZnO-NPs treated cells. ZnO NPs also increased tumor necrosis factor (TNF)-α expression and secretion, which were inhibited by the blockade of Egr-1 expression. CONCLUSIONS The present study demonstrated that ZnO-NPs might induce inflammatory response via ROS-ERK-Egr-1 pathway in human keratinocytes.

Influence of surface charge of gold nanorods on skin penetration

The skin plays an important role as a protective barrier against toxic environments and also is a route of drug administration. In spite of evidence for and interest in the skin penetration of nanoparticles, no study has examined the effect of nanoparticle surface charge on percutaneous absorption. In this study, we investigated the effect of surface charges of gold nanorods (GNs) on skin penetration.

Thymic stromal lymphopoietin downregulates filaggrin expression by signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase (ERK) phosphorylation in keratinocytes

IL-33–activated mast cells and ILC2s, and may be involved in severe asthma via the recruitment of neutrophils and smooth muscle activation. Furthermore, the presence of other immune cells in the airway in an IL-33 milieu may result in an abundance of non–type 2 mediators, which could affect differential gene expression not otherwise seen in the coculture system. Thus, further studies need to be conducted in vivo to examine the effects of anti–IL-13 on airway inflammation, mucus expression, and hyperreactivity in response to IL-33. In conclusion, we have shown that IL-33–activated mast cells and ILC2s drive predominantly IL-13–regulated gene expression when cocultured with NHBE cells, which initiates a transcriptional program that can subsequently exacerbate airway pathology and contribute to fibrosis, eosinophilia, and mucous metaplasia. Although mast cells and ILC2s produce a diverse set of cytokines and other mediators of intercellular communication in response to IL-33, the predominant effect on airway epithelium in this in vitro coculture system is mediated by IL-13.

The potential for skin irritation, phototoxicity, and sensitization of ZnO nanoparticles

In spite of widely use of zinc oxide (ZnO) nanoparticles (NPs) in cosmetic industry and in our daily lives, insufficient studies have evaluated the potential of their toxic response. This study was conducted to investigate the potential of cytotoxicity induced by ZnO NPs, especially influences of the surface charge and different particle size. Assessment of potential of skin irritation was estimated using human skin equivalent model (HSEM), and an animal model. And the evaluation of skin phototoxicity was tested by the 3T3 neutral red uptake test. Lastly, the potential of skin sensitization was evaluated by a local lymph node assay (LLNA). The results from this study demonstrated that ZnO NPs are not dermal sensitizers and do not induce skin irritation. But they may produce phototoxicity.

Oxidative stress and apoptosis induced by ZnO nanoparticles in HaCaT cells

Zinc oxide (ZnO) nanoparticles (NPs) are used in the cosmetic industry in cosmetics and sunscreen. ZnO NPs have been reported to elicit various adverse cellular effects, including cytotoxicity. However, the underlying mechanisms of these adverse effects have not been fully characterized. To investigate the potential of cytotoxicity induced by ZnO NPs, we evaluated cytosolic reactive oxygen species levels in human keratinocyte HaCaT cells treated with ZnO NPs having different surface charges and particle sizes. A short period of treatment (30 min) with 100 nm ZnO NPs resulted in a greater increase of cytosolic ROS levels, compared to treatment with 20 nm ZnO NPs at the same concentration. During a long period of treatment (24 h) with ZnO NPs, intracellular ROS was increased in cells treated with 20 μg/mL 20 nm (+/−) charged ZnO. No significant difference according to differences in surface charge was observed. In addition, total levels of caspase-7 and PARP were decreased by ZnO NPs. These results demonstrated that ZnO NPs could induce ROS mediated apoptosis.

Cigarette smoke‐induced early growth response‐1 regulates the expression of the cysteine‐rich 61 in human skin dermal fibroblasts

Abstract:  Tobacco smoke is known to be an element contributing to accelerate premature skin ageing. Cysteine‐rich 61 (Cyr61) is a member of the connective tissue factor CCN (Cyr61, CTGF and Nov) family, and early growth response‐1 (Egr‐1) is a generally expressed member of the zinc‐finger family of transcription factors. To investigate the regulatory potential of Egr‐1 on expression of Cyr61 by smoking, this study examined the hypothesis that cigarette smoke‐induced Egr‐1 induces expression of Cyr61 in human skin dermal fibroblasts (HSDF). HSDF were exposed to different concentrations of cigarette smoke extract (CSE) for 24 h; a cytotoxicity assay was then performed for the detection of cell proliferation. Results of Western blot and reverse transcription‐polymerase chain reaction (RT‐PCR) showed that CSE induces a transient synthesis of Egr‐1 in HSDF. Cyr61 mRNA and protein levels showed a marked increase in a time‐dependent manner after CSE exposure. Following transfection with an Egr‐1 overexpression vector, HSDF showed increased activity of the Cyr61 promoter in a dose‐dependent manner. Using Egr‐1 interfering RNA, we confirmed that CSE‐induced Cyr61 expression was dependent on Egr‐1 expression. Findings of this study indicate that Egr‐1‐dependent induction of Cyr61 may contribute to premature skin ageing by smoking.