The properties of mucus in a person with asthma can alter with disease process so that it may lead to the airway embolism. Fe2O3 nanoparticles can be used for drug delivery. Up till now, however, little is known about how the Fe2O3 nanoparticles influence the properties of airway mucus. In this study, Fe2O3 nanoparticles were dispersed with ultrasound, and the morphological properties were measured with scanning electron microscope, atomic force microscope and nanometer laser particle size and zeta potential analyzer. Then the dispersed Fe2O3 nanoparticles were added to the simulated asthma airway mucus with different final concentration (0.03, 0.3, and 0.4 mg/mL). The measurements of flow curve, yield stress, large amplitude oscillatory shear (LAOS) and shock scanning were carried out with a rotational rheometer. Experimental results showed that the Fe2O3 nanoparticles reduced the zero shear viscosity of simulated asthma airway mucus. With increase of shear rate, the wind speed of mucus was reduced. The yield stress of simulated asthma airway mucus was 19.0 Pa, but the yield stresses of experimental group (0.03, 0.3 and 0.4 mg/mL) were 17.0, 0.99, and 0.7 Pa, respectively. The results showed that the viscoelastic modulus of asthma airway mucus treated with Fe2O3 nanoparticles were changed obviously as measured with large amplitude scanning and frequency scanning. By adopting the method of optical phase microscopy, we found that different structures of simulated airway mucus were absorbed. The results showed Fe2O3 nanoparticles distroyed mucus structure. The experimental results proved that Fe2O3 nanoparticles could change the rheological characteristics of simulated asthma airway mucus. This experimental result would lay a foundation for the further development of airway mucus sticky agent based on the function of Fe2O3 nanoparticles.
Objective To investigate whether interleukin-1 receptor associated kinase (IRAK) participates the airway mucus hypersecretion induced by lipopolysaccharide (LPS). Methods The expression of Toll-like receptor (TLR)-4 or IRAK was down regulated by the transfection of specific small interfering RNA (siRNA). The transcription level of mucin 5AC (MUC5AC) mRNA as well as the secretion level of MUC5AC protein were judged by reverse transcription polymerase chain reaction (RT-PCR) and enzyme linked immunosorbent assay (ELISA), respectively. The activity of signaling molecules involved in TLR-4 associated pathway, such as the phosphorylated IRAK, nuclear translocation of NF-κB p65, was analyzed by Western blot. Results The level of intracellular phosphorylated IRAK was increased by stimulation of LPS in BEAS-2B cells. However, down-regulation of TLR-4 by siRNA could partially attenuate the additional phosphorylation of IRAK induced by LPS (P<0.05). LPS elicited a nuclear translocation of NF-κB p65 in BEAS-2B cells, which could be partially blocked by the down-regulation of TLR-4 or IRAK. With RT-PCR, an increased expression level of MUC5AC mRNA was discovered in wild-type BEAS-2B cells (0.82±0.09) than TLR-4 defect cells (0.36±0.05), IRAK defect cells (0.48±0.05) and IRAK inhibitor pretreated cells (0.57±0.07) (all P<0.05). Meanwhile, according to ELISA, an increased secretion level of MUC5AC protein was recorded in wild-type BEAS-2B cells [(0.76±0.09) μg/L] than TLR-4 defect cells [(0.33±0.04) μg/L], IRAK defect cells [(0.42±0.05) μg/L] and IRAK inhibitor pretreated cells [(0.51±0.06) μg/L] (all P<0.05). Conclusion As an crucial regulator of TLR dependent signaling pathway, IRAK may participate the airway mucus over-synthesis induced by LPS.