In-Hong Choi

Multifunctional Nanoparticles for Combined Doxorubicin and Photothermal Treatments

To facilitate combined doxorubicin and photothermal treatments, we developed doxorubicin-loaded poly(lactic-co-glycolic acid)-gold half-shell nanoparticles (DOX-loaded PLGA-Au H-S NPs) by depositing Au films on DOX-loaded PLGA NPs. As the PLGA NPs biodegraded, DOX was released, and heat was locally generated upon near-infrared (NIR) irradiation due to NIR resonance of DOX-loaded PLGA H-S NPs. Compared with chemotherapy or photothermal treatment alone, the combined treatment demonstrated a synergistic effect, resulting in higher therapeutic efficacy and shorter treatment times. Since our NPs selectively deliver both heat and drug to tumorigenic regions, they may improve the therapeutic effectiveness with minimal side effects.

The effects of sub-lethal concentrations of silver nanoparticles on inflammatory and stress genes in human macrophages using cDNA microarray analysis.

Because of the limited information on size-dependent particle-mediated effects, the present study was conducted to determine if the changes in induced protein expression between 5 nm silver nanoparticles and 100 nm particles after exposure to sub-lethal concentrations. A total of 28,000 cDNA profiles were screened using 5 nm silver nanoparticles and 100 nm silver nanoparticles in a macrophage cell line. Based on results obtained from cDNA microarray we also assessed protein levels of hemeoxygenase-1 (HO-1), heat shock protein-70 (HSP-70) and interleukin-8 (IL-8), which were shown to significantly increase. Together with results obtained using N-acetylcystein (NAC), we were able to clearly show that low level and early stage exposure to 5 nm silver nanoparticles, but not 100 nm, induces expression of IL-8 as well as stress genes against reactive oxygen species (ROS). Therefore, we provide important data to understand and identify the early effects of silver nanoparticles on the immune system.

Vascular tube formation and angiogenesis induced by polyvinylpyrrolidone-coated silver nanoparticles.

Silver nanoparticles (AgNPs) are one of the most commonly used nanomaterials due to their antibacterial properties. In this study, we examined the effects of polyvinylpyrrolidone (PVP)-coated AgNPs (average size 2.3nm) on angiogenesis in both an in vivo model and an in vitro endothelial cell line, SVEC4-10. Increased angiogenesis was detected around the injection site of AgNP-containing Matrigel in vivo. AgNPs also increased the infiltration of endothelial cells and the hemoglobin (Hb) content in AgNP-Matrigel plugs implanted into mice. AgNPs induced endothelial cell tube formation on growth factor-reduced Matrigel, production of reactive oxygen species (ROS), and production of angiogenic factors, such as vascular endothelial growth factor (VEGF) and nitric oxide (NO), in SVEC4-10 cells. In addition, AgNPs promoted the activation of FAK, Akt, ERK1/2, and p38, which are all involved in VEGF receptor (VEGFR)-mediated signaling. Finally, AgNP-treated tumors caused angiogenesis around tumors in B16F10 melanomas after they were injected into mice, and the Hb concentration in the tumors increased in a concentration-dependent manner with AgNP treatment. Thus, our study suggests that exposure to AgNPs can cause angiogenesis through the production of angiogenic factors.

Double-stranded RNA mediates interferon regulatory factor 3 activation and interleukin-6 production by engaging Toll-like receptor 3 in human brain astrocytes

Toll‐like receptor 3 (TLR3) participates in the innate immune response by recognizing viral pathogens. In this study, human brain astrocytes were found to constitutively express TLR3, and this expression was increased by interferon‐γ (IFN‐γ) or double‐stranded RNA (dsRNA). Treatment employing dsRNA in astrocytes induced IFN regulatory factor 3 (IRF3) phosphorylation, dimer formation and nuclear translocation followed by STAT1 activation. This treatment also activated nuclear factor‐κB, p38 and c‐Jun N‐terminal kinase significantly, while activating extracellular signal‐regulated kinase to a lesser extent. Treatment with anti‐TLR3 antibody inhibited dsRNA‐mediated interleukin‐6 (IL‐6) production. In the presence of mitogen‐activated protein kinase inhibitors, astrocytes failed to secrete IL‐6 in response to dsRNA treatment. Therefore, dsRNA‐induced IL‐6 production is dependent on mitogen‐activated protein kinases and type I IFN production is dependent on IRF3 in brain astrocytes. These results suggest that brain inflammation, which produces inflammatory cytokines and type I IFNs, may enhance TLR3 expression in astrocytes. Additionally, upregulated TLR3 might modulate inflammatory processes by producing proinflammatory cytokines.

Hydrogen peroxide triggers the expression of Fas/FasL in astrocytoma cell lines and augments apoptosis

Fas expression increases in perinecrotic areas of glioblastoma. In this study the up-regulation of Fas/FasL by oxidative stress was shown. H(2)O(2) exposure increased Fas expression in two astrocytoma cell lines and cells became sensitive to agonistic anti-Fas antibody. FasL was up-regulated in astrocytoma cells. Apoptosis of Molt-4 cells was augmented by astrocytoma cells pretreated with H(2)O(2). Our findings suggest up-regulation of Fas in astrocytoma cells may lead them to be sensitive to apoptosis when cells are in oxidative stress. Whereas, the up-regulation of FasL may render astrocytoma cells cytotoxic to neighboring brain tissues and infiltrating immune cells.

Phagocytosis and Endocytosis of Silver Nanoparticles Induce Interleukin-8 Production in Human Macrophages

Phagocytosis or endocytosis by macrophages is critical to the uptake of fine particles, including nanoparticles, in order to initiate toxic effects in cells. Here, our data enhance the understanding of the process of internalization of silver nanoparticles by macrophages. When macrophages were pre-treated with inhibitors to phagocytosis, caveolin-mediated endocytosis, or clathrin-mediated endocytosis, prior to exposure to silver nanoparticles, Interleukin-8 (IL-8) production was inhibited. Although cell death was not reduced, the inflammatory response by macrophages was compromised by phagocytosis and endocytosis inhibitors.

The Impact of Nanomaterials in Immune System

As a nanotechnology has been actively applied to the overall areas of scientific fields, it is necessary to understand the characteristic features, physical behaviors and the potential effects of exposure to nanomaterials and their toxicity. In this article we review the immunological influences induced by several nanomaterials and emphasize establishment of the animal models to estimate the impact of these nanomaterials on development of immunological diseases.

Acute exposure to silica nanoparticles aggravate airway inflammation: different effects according to surface characteristics.

Silica nanoparticles (SNPs) are widely used in many scientific and industrial fields despite the lack of proper evaluation of their potential toxicity. This study examined the effects of acute exposure to SNPs, either alone or in conjunction with ovalbumin (OVA), by studying the respiratory systems in exposed mouse models. Three types of SNPs were used: spherical SNPs (S-SNPs), mesoporous SNPs (M-SNPs), and PEGylated SNPs (P-SNPs). In the acute SNP exposure model performed, 6-week-old BALB/c female mice were intranasally inoculated with SNPs for 3 consecutive days. In the OVA/SNPs asthma model, the mice were sensitized two times via the peritoneal route with OVA. Additionally, the mice endured OVA with or without SNP challenges intranasally. Acute SNP exposure induced significant airway inflammation and airway hyper-responsiveness, particularly in the S-SNP group. In OVA/SNPs asthma models, OVA with SNP-treated group showed significant airway inflammation, more than those treated with only OVA and without SNPs. In these models, the P-SNP group induced lower levels of inflammation on airways than both the S-SNP or M-SNP groups. Interleukin (IL)-5, IL-13, IL-1β and interferon-γ levels correlated with airway inflammation in the tested models, without statistical significance. In the mouse models studied, increased airway inflammation was associated with acute SNPs exposure, whether exposed solely to SNPs or SNPs in conjunction with OVA. P-SNPs appear to be relatively safer for clinical use than S-SNPs and M-SNPs, as determined by lower observed toxicity and airway system inflammation.

CKD712, (S)-1-(α-naphthylmethyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, inhibits the lipopolysaccharide-stimulated secretion of HMGB1 by inhibiting PI3K and classical protein kinase C.

CKD712, (S)-1-(α-naphthylmethyl)-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, was considered as a new effective drug candidate to sepsis, based on its anti-inflammatory activity. It was reported that CKD712 inhibited various signal pathways which play a key role in production of proinflammatory cytokines. Here, we examined the effect of CKD712 on the secretion of high mobility group box 1 (HMGB1), which is one of the proinflammatory cytokines. CKD712 can reduce Gram-negative lipopolysaccharide (LPS)- and Gram-positive lipoteichoic acid (LTA)-stimulated HMGB1 secretion in RAW264.7 and human peripheral blood monocytes (PBMo), and also reduce LPS-induced nucleocytoplasmic translocation of HMGB1 1h before or after LPS treatment. CKD712 could dose-dependently inhibit the activation of PI3K and PI3K-dependent kinase 1 (PDK1), which are involved in HMGB1 secretion signaling pathway. In addition, CKD712 inhibited classical protein kinase C (cPKC), the effective kinase for phosphorylation of HMGB1 for secretion, however, had no effect on histone acetyl-transferase activity, which is another mechanism known for HMGB1 secretion. Thus, we suggest that CKD712 could inhibit LPS- and LTA-stimulated HMGB1 secretion through the inhibition of HMGB1 phosphorylation by inhibiting PI3K-PKC signaling pathway.

Over-expression of S100B protein in children with cerebral palsy or delayed development

S100B protein plays a role in promoting the maturation of a variety of neurons in many different CNS regions. Behavioral dysfunction in S100B over-expressed transgenic mice and the chronic elevation of S100B in Downs syndrome and in schizophrenia suggest that S100B over-expression is related to abnormal brain function. Therefore, we believed that the over-expression of S100B protein might be implicated in developmental brain dysfunction. The purpose of this study was to evaluate the serum S100B protein levels in patients with developmental brain dysfunction, such as cerebral palsy and delayed development, and to determine the clinical relevance of serum S100B protein in these patients. The mean values of serum S100B protein were significantly increased in both conditions. Patients with cerebral palsy had a S100B protein level of 3455.8 +/- 5004.6 ng/L and those with delayed development of 2557.0 +/- 2321.0 ng/L, compared with a normal control level of 583.8 +/- 483.0 ng/L (P < 0.05). The over-expression of S100B (defined as the normal mean plus three standard deviations) was found in 47.1% of the total patient group (delayed development (47.5%) and cerebral palsy (47.0%)). The frequency of over-expression was not significantly related to clinical diagnosis, disease severity or to brain MRI findings. However, patients who had periventricular leukomalacia by brain MRI showed a wide range and very high levels of S100B exceeding 10,000 ng/L in some cases. These findings suggest that the pathogenesis implied by the over-expression of S100B protein during brain development may play a role in developmental brain dysfunction.