Chen Chen Lee

Shikonin inhibits maturation of bone marrow-derived dendritic cells and suppresses allergic airway inflammation in a murine model of asthma

BACKGROUND AND PURPOSE Shikonin exhibits a wide range of anti‐inflammatory actions. Here, we assessed its effects on maturation of murine bone marrow‐derived dendritic cells (BM‐DCs) and on allergic reactions in a murine model of asthma.

Inhibition of high-mobility group box 1 in lung reduced airway inflammation and remodeling in a mouse model of chronic asthma.

The role of high-mobility group box 1 (HMGB1) in chronic allergic asthma is currently unclear. Both airway neutrophilia and eosinophilia and increase in HMGB1 expression in the lungs in our murine model of chronic asthma. Inhibition of HMGB1 expression in lung in ovalbumin (OVA)-immunized mice decreased induced airway inflammation, mucus formation, and collagen deposition in lung tissues. Analysis of the numbers of CD4(+) T helper (Th) cells in the mediastinal lymph nodes and lungs revealed that Th17 showed greater increases than Th2 cells and Th1 cells in OVA-immunized mice; further, the numbers of Th1, Th2, and Th17 cells decreased in anti-HMGB1 antibody (Ab)-treated mice. In OVA-immunized mice, TLR-2 and TLR-4 expression, but not RAGE expression, was activated in the lungs and attenuated after anti-HMGB1 Ab treatment. The results showed that increase in HMGB1 release and expression in the lungs could be an important pathological mechanism underlying chronic allergic asthma and HMGB1 might a potential therapeutic target for chronic allergic asthma.

Motorcycle exhaust particles up-regulate expression of vascular adhesion molecule-1 and intercellular adhesion molecule-1 in human umbilical vein endothelial cells

Epidemiological studies have shown that there is a strong correlation between atherosclerosis and ambient air pollution. In this study, we found that motorcycle exhaust particles (MEP) induced adhesion between cells of the human monocytic leukemia cell line (THP-1) and human umbilical vein endothelial cells (HUVECs) in a time-and dose-dependent manner. In addition, MEP treatment induced both mRNA and protein expression of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) in HUVECs. The IκB degradation and p65 nuclear translocation was found in MEP-treated HUVECs, suggested the involvement of nuclear factor-κB (NF-κB). MEP-induced VCAM-1 and ICAM-1 protein expression was inhibited by NF-κB inhibitor BAY 11-7085. Oxidative stress was also involved in the signaling of VCAM-1 and ICAM-1 expression. MEP treatment caused hydrogen peroxide and superoxide formation. Pretreatment with α-tocopherol could inhibit MEP-induced reactive oxygen intermediates generation and suppressed MEP-induced IκB degradation and adhesion molecules expression. Furthermore, the carbon black (CB) nanoparticles with different diameters could induce VCAM-1 and ICAM-1 protein expression; however, polycyclic aromatic hydrocarbons (PAHs) only increased the expression of ICAM-1 but not that of VCAM-1 in HUVECs. In this study, we found that MEPs could induce ICAM-1 and VCAM-1 expression through oxidative stress and NF-κB activation in HUVECs.

Gold Nanoparticles Increase Endothelial Paracellular Permeability by Altering Components of Endothelial Tight Junctions, and Increase Blood-Brain Barrier Permeability in Mice

Gold nanoparticles (Au-NPs) are being increasingly used as constituents in cosmetics, biosensors, bioimaging, photothermal therapy, and targeted drug delivery. This elevated exposure to Au-NPs poses systemic risks in humans, particularly risks associated with the biodistribution of Au-NPs and their potent interaction with biological barriers. We treated human umbilical vein endothelial cells with Au-NPs and comprehensively examined the expression levels of tight junction (TJ) proteins such as occludin, claudin-5, junctional adhesion molecules, and zonula occludens-1 (ZO-1), as well as endothelial paracellular permeability and the intracellular signaling required for TJ organization. Moreover, we validated the effects of Au-NPs on the integrity of TJs in mouse brain microvascular endothelial cells in vitro and obtained direct evidence of their influence on blood-brain barrier (BBB) permeability in vivo. Treatment with Au-NPs caused a pronounced reduction of PKCζ-dependent threonine phosphorylation of occludin and ZO-1, which resulted in the instability of endothelial TJs and led to proteasome-mediated degradation of TJ components. This impairment in the assembly of TJs between endothelial cells increased the permeability of the transendothelial paracellular passage and the BBB. Au-NPs increased endothelial paracellular permeability in vitro and elevated BBB permeability in vivo. Future studies must investigate the direct and indirect toxicity caused by Au-NP-induced endothelial TJ opening and thereby address the double-edged-sword effect of Au-NPs.

Motorcycle exhaust particles induce IL-8 production through NF-κB activation in human airway epithelial cells

Motorcycle exhaust particles (MEP) are among the major air pollutants, especially in urban area of Taiwan. In our previous study, data showed that MEP induce proinflammatory and proallergic response profiles in BALB/c mice. Effects of MEP on interleukin (IL)-8 production in A549 human airway epithelial cells were further investigated in this study. It was found that MEP enhanced IL-8 protein and mRNA expression in human epithelial cells. Pretreatment with an NF-κB inhibitor (1 mM PDTC), extracellular signal-regulated kinase (ERK) inhibitor (50 μM PD98059), JNK inhibitor (25 μM SP600125), p38 inhibitor (2 μM SB203580), and three antioxidants (500 U/ml superoxide dismutase [SOD], 50 μM vitamin E, 10 mM N-acetylcysteine [NAC]) attenuated the MEP-induced increase in IL-8 production. Through further, direct detection of nuclear factor (NF)-κB activation in epithelial cells using immunoblotting of nuclear p65 and NF-κB reporter assay, data showed that MEP induced nuclear translocation of p65 and enhancement of NF-κB luciferase gene expression. MEP also induced activation of ERK, JNK, and p38 signaling pathways and produced an increase of oxidative stress in A549 cells. By using mitogen-activated protein kinase (MAPK) inhibitors and antioxidant, it was demonstrated that ERK inhibitor, JNK inhibitor, and antioxidants but not p38 inhibitor attenuated the MEP-induced increase in NF-κB reporter activity. In conclusion, evidence shows that filter-trapped particles emitted from unleaded gasoline-fueled, two-stroke motorcycle engines induce an increase in IL-8 production by activation of NF-κB in human airway epithelial cells.

High mobility group box 1-induced epithelial mesenchymal transition in human airway epithelial cells

Epithelial–mesenchymal transition (EMT) is implicated in bronchial remodeling and loss of lung function in chronic inflammatory airway diseases. Previous studies showed the involvement of the high mobility group box 1 (HMGB1) protein in the pathology of chronic pulmonary inflammatory diseases. However, the role of HMGB1 in EMT of human airway epithelial cells is still unclear. In this study, we used RNA sequencing to show that HMGB1 treatment regulated EMT-related gene expression in human primary-airway epithelial cells. The top five upregulated genes were SNAI2, FGFBP1, VIM, SPARC (osteonectin), and SERPINE1, while the downregulated genes included OCLN, TJP1 (ZO-1), FZD7, CDH1 (E-cadherin), and LAMA5. We found that HMGB1 induced downregulation of E-cadherin and ZO-1, and upregulation of vimentin mRNA transcription and protein translation in a dose-dependent manner. Additionally, we observed that HMGB1 induced AKT phosphorylation, resulting in GSK3β inactivation, cytoplasmic accumulation, and nuclear translocation of β-catenin to induce EMT in human airway epithelial cells. Treatment with PI3K inhibitor (LY294006) and β-catenin shRNA reversed HMGB1-induced EMT. Moreover, HMGB1 induced expression of receptor for advanced glycation products (RAGE), but not that of Toll-like receptor (TLR) 2 or TLR4, and RAGE shRNA inhibited HMGB1-induced EMT in human airway epithelial cells. In conclusion, we found that HMGB1 induced EMT through RAGE and the PI3K/AKT/GSK3β/β-catenin signaling pathway.

Zinc oxide nanoparticles impair bacterial clearance by macrophages

AIM The extensive development of nanoparticles (NPs) and their widespread employment in daily life have led to an increase in environmental concentrations of substances that may pose a biohazard to humans. The aim of this work was to examine the effects of zinc oxide nanoparticles (ZnO-NPs) on the hosts pulmonary immune system response to nontypeable Haemophilus influenzae (NTHi) infection. MATERIALS & METHODS A murine infection model was employed to assess pulmonary inflammation and bacterial clearance in response to exposure to ZnO-NPs. The molecular mechanisms underlying ZnO-NP-impaired macrophage activation were investigated. RESULTS Treatment with ZnO-NPs impaired macrophage activation, leading to a delay in NTHi clearance in the bronchial alveolar lavage fluids and lungs. Exposure to ZnO-NPs followed by NTHi challenge decreased levels of nitric oxide compared with NTHi infection alone. The effects of ZnO-NPs involved downregulation of NTHi-activated expression of inducible nitric oxide synthase and the translocation of active NF-kB into the nucleus. CONCLUSION These results demonstrate that exposure to ZnO-NPs can impair innate immune responses and attenuate macrophage responses to bacterial infection.

Shikonin inhibited mitogen-activated IL-4 and IL-5 production on EL-4 cells through downregulation of GATA-3 and c-Maf induction

AIM To investigate the effects of shikonin on phorbol myristate acetate (PMA) plus cyclic adenosine monophosphate (cAMP)-induced T helper (T(H)) 2 cell cytokine production, and the underlying mechanism. MAIN METHODS We used activated EL-4 murine T-lymphoma cells, which produce interleukin (IL)-4 and IL-5, but not interferon (IFN)-γ, as T(H)2 cell-like cells and treated them with PMA+cAMP to investigate the effects of shikonin on T(H)2 cytokines, transcriptional factors, and the related mitogen-activated protein kinase (MAPK)/nuclear factor (NF)-κB signaling pathway. KEY FINDINGS The data show that shikonin inhibited the PMA+cAMP-induced mRNA and protein expression of IL-4 and IL-5 via the downregulation of GATA-binding protein-3 (GATA-3) and c-musculoaponeurotic fibrosarcoma (Maf) but not T-box expressed in T cells (T-bet). Moreover, shikonin suppressed the phosphorylation of p38, inhibitor of κB (IκB) kinase (IKK)-β and IκB-α, and the subsequent IκB-α degradation induced by PMA+cAMP; however, the PMA+cAMP-induced phosphorylation of extracellular signal-related kinase (ERK), which resulted in minor inhibition and phosphorylation of c-Jun N-terminal kinase (JNK), seemed to be unaffected by shikonin treatment. SIGNIFICANCE This study suggests that downregulation of GATA-3 and c-Maf via the suppression of p38, IKK-β and IκB-α phosphorylation might contribute to the inhibitory effect of shikonin on mitogen-induced IL-4 and IL-5 production in EL-4T cells. Furthermore, shikonin is a potential drug for treating allergic diseases.

Cytoplasmic aryl hydrocarbon receptor regulates glycogen synthase kinase 3 beta, accelerates vimentin degradation, and suppresses epithelial–mesenchymal transition in non-small cell lung cancer cells

Aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, has been studied extensively in carcinogenesis through the genomic pathway. In recent years, AHR has also been reported to exert positive or negative effects on epithelial–mesenchymal transition (EMT), the crucial step in tumor malignant progression. However, the detailed mechanism remains controversial. Analysis of AHR-expression levels in non-small cell lung cancer cell lines and lung cancer tissues revealed an inverse correlation between AHR protein levels and tumor cell invasion and metastasis. Overexpression of wild-type AHR in H1299 cells (AHR poorly expressed, potently invasive) not only accelerated mesenchymal vimentin degradation, but also prevented cell invasion in vitro and in vivo. In the absence of AHR agonists, the overexpressed AHR protein was predominantly localized in the cytoplasm, where it interacted with vimentin and functioned as an E3 ubiquitin ligase. A 6-h incubation with the proteasome inhibitor MG-132 fully rescued vimentin from AHR-mediated proteasomal degradation. In AHR-overexpressing H1299 cells, either vimentin degradation or invasive suppression could be reversed when glycogen synthase kinase 3 beta (GSK3β) was inactivated by CHIR-99021 treatment. In contrast, silencing of AHR in A549 cells (AHR highly expressed, weakly invasive) resulted in the downregulation of epithelial biomarkers (E-cadherin and claudin-1), augmentation of mesenchymal vimentin level, and GSK3β Ser-9 hyper-phosphorylation, which led to enhanced invasiveness. This work demonstrates that cytoplasmic, resting AHR protein may act as an EMT suppressor via a non-genomic pathway. Depletion of cytoplasmic AHR content represents a potential switch for EMT, thereby leading to the scattering of tumor cells.

Ligand independent aryl hydrocarbon receptor inhibits lung cancer cell invasion by degradation of Smad4

The aryl hydrocarbon receptor (AhR) is a ligand-dependent-activated transcriptional factor that regulates the metabolism of xenobiotic and endogenous compounds. Although AhR plays a crucial role in air toxicant-induced carcinogenesis, AhR expression was shown to negatively regulate tumorigenesis. Therefore, in the present study, we investigated the effect of AhR without ligand treatment on cancer invasion in lung cancer cell lines. Lung cancer cells expressing lower levels of AhR showed higher invasion ability (H1299 cells) compared with cells expressing higher levels of AhR (A549 cells). Overexpression of AhR in H1299 cells inhibited the invasion ability. We found that vimentin expression was inhibited in AhR-overexpressing H1299 cells. Additionally, the expression of EMT-related transcriptional factors Snail and ID-1 decreased. Interestingly, we found that Smad4 degradation was induced in AhR-overexpressing H1299 cells. Our data showed that AhR could interact with Jun-activation domain binding protein (Jab1) and Smad4, which may cause degradation of Smad4 by the proteasome. Our data suggest that AhR affects the transforming growth factor-β signaling pathway by inducing Smad4 degradation by the proteasome and suppressing tumor metastasis via epithelial to mesenchymal transition reduction in lung cancer cells.