Distinct TLR-mediated pathways regulate house dust mite-induced allergic disease in the upper and lower airways.

BACKGROUND: Allergic rhinitis (AR) and asthma are 2 entities of allergic airway diseases that frequently occur together, which is referred to as united airways. In contrast to this general concept, we hypothesized that innate immunity of the upper and lower airways is respectively distinctive, because the immunologic conditions of the nasal and lung mucosa as well as the functions of the immune cells within their epithelia are different. OBJECTIVE: We wanted to identify distinctive mechanisms of innate immunity in the nose and lung mucosa, which are responsible for house dust mite (HDM)-induced AR and allergic asthma (AA), respectively. METHODS: We constructed a mouse model of AR or AA induced by sensitization and consequent provocation with HDM extracts. RESULTS: HDM-derived ß-glucans, rather than LPS, were proven to be essential to activating innate immunity in the nasal mucosa and triggering AR, which depended on Toll-like receptor 2 (TLR2), but not on TLR4; however, the LPS/TLR4 signaling axis, rather than ß-glucans/TLR2, was critical to HDM-induced AA. These differences were attributed to the specific role of ß-glucans and LPS in inducing the surface expression of TLR2 and TLR4 and their translocation to lipid rafts in nasal and bronchial epithelial cells, respectively. We also showed that dual oxidase 2-generated reactive oxygen species mediate both ß-glucan-induced TLR2 activation and LPS-induced TLR4 activation. CONCLUSIONS: We describe a novel finding of distinctive innate immunity of the nose and lungs, respectively, which trigger AR and AA, by showing the critical role of HDM-induced TLR activation via dual oxidase 2-mediated reactive oxygen species.

ICAM-3 endows anticancer drug resistance against microtubule-damaging agents via activation of the ICAM-3-AKT/ERK-CREB-2 pathway and blockage of apoptosis.

In a previous study, we showed that induction of ICAM-3 endows radioresistance in cervical cancer [1]. To ascertain whether ICAM-3 also promotes anticancer drug resistance, mock control (H1299/pcDNA3) or ICAM-3-expressing stable transfectants (H1299/ICAM-3) of the non-small cell lung cancer (NSCLC) cell line, NCI-H1299, were generated and treated with the microtubule-damaging agents, paclitaxel (TXL) and vincristine (VCS). TXL-/VCS-treated H1299/ICAM-3 cells showed significantly lower levels of apoptosis, activation of caspases-3, 8 or 9, and decrease in anti-apoptotic protein levels, compared to H1299/pcDNA3 cells. Our data clearly indicate that ICAM-3 promotes drug resistance via inhibition of apoptosis. We additionally showed that Akt, ERK, and CREB-2 are located downstream of ICAM-3, and activation of the ICAM-3-Akt/ERK-CREB-2 pathway induces resistance against TXL and VCS. ICAM-3-expressing stable NCI-H460/ICAM-3 transfectant cells and radioresistant SiHa cells endogenously overexpressing ICAM-3 additionally showed drug resistance against TXL and VCS via activation of the ICAM-3-Akt/ERK-CREB-2 pathway. The finding that ICAM-3 endows drug resistance as well as radioresistance supports its potential utility as a major therapeutic target against cancer.

Luteolin acts as a radiosensitizer in non­small cell lung cancer cells by enhancing apoptotic cell death through activation of a p38/ROS/caspase cascade.

To improve radiation therapy, the development of effective radiosensitizer is required. Fifty percent inhibitory concentration (IC50) values of 3',4',5',7'­tetrahydroxyflavone (luteolin) against NCI­H460 and ­H1299 non­small cell lung cancer (NSCLC) cells were determined using 3­(4,5­dimethylthiazol­2­yl)­2,5­diphenyltetrazolium bromide (MTT) assays. Radiosensitizing activity was assessed in vitro by treating cells with luteolin prior to irradiation of γ­ionizing radiation (IR), and performing cell count and clonogenic assays. Cell signaling pathways involved in the radiosensitizing effects of luteolin were examined using propidium iodide (PI) uptake, reactive oxygen species (ROS) detection and immunoblot assays, with or without specific chemical inhibitors. Apoptotic cell death was confirmed by PI uptake and immunoblot assays. In vivo radiosensitizing activity was tested using an NCI­H460 cell xenograft model in nude mice. Tumor size was measured and apoptosis was determined with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay in animals in four treatment groups: mock­treated control, luteolin only, IR only, and luteolin plus IR. Treatment with luteolin or IR induced NSCLC cell death in vitro, but the combination of luteolin pre­treatment and IR was more effective than either agent alone, yielding dose enhancement ratios (DERs) of 1.22 and 1.35 for NCI­H460 and ­H1299 cells, respectively. Combined treatment with luteolin and IR enhanced apoptotic cell death in association with downregulation of B­cell lymphoma 2 (Bcl­2) and activation of caspase­3, ­8, and ­9; it also induced phosphorylation of p38 mitogen­activated protein kinase (MAPK) and ROS accumulation. Inhibition of p38 MAPK decreased ROS production, and inhibition of either p38 MAPK or ROS production attenuated apoptotic cell death and activation of caspase­8 and ­9. In a xenograft model, tumor growth was delayed by 21.8 days in the luteolin/IR combination group compared with controls, and apoptotic cell death was increased. The enhancement factor of the luteolin and IR combination was 1.83. Collectively, these findings indicate that luteolin acts as a radiosensitizer by enhancing apoptotic cell death through activation of a p38/ROS/caspase cascade.