The Langmuir monolayer behavior of (di)alkoxy-substituted precursor poly(p-phenylenevinylenes) (PPVs) with a methoxy-leaving group was studied. The average orientation of the aromatic ring and the ether groups at the air-water interface was elucidated by external FT-infrared reflection spectroscopy measurements at the air-water interface combined with FT-IR computer simulations. The aromatic rings of the precursors, except those of the dibutoxy-substituted one, take on, directly after spreading, an almost perpendicular orientation to the water subphase. The isotherms of these precursors showed no special transitions, and these polymers can be considered to be in a condensed or 2-D collapsed state with lateral cohesive π-π interactions between the aromatic rings as the most prominent interaction leading to this condensed state. The aromatic rings of the dibutoxy-substituted precursor are lying flat at the water surface at large areas per repeating unit and can be considered to be in the expanded state directly after spreading. The isotherm of this precursor showed two transitions because here the chain conformation is predominantly determined by the butyl chains and not by the main chain.

The Langmuir monolayer stability and transfer properties of (di)alkoxy-substituted precursor PPVs were studied. All polymers formed stable monolayers, but the packing of the monomeric units in the monolayer depended strongly on the substituents. The less closely packed monolayers can be transferred with the Langmuir-Blodgett technique, while the closely packed monolayers, with strong π-π interaction between the aromatic rings, can only be transferred with the Langmuir-Schaefer technique due to the stiffness of the monolayers. Transmission and grazing incidence reflection FT-IR spectroscopy in combination with IR spectra computer simulations revealed that in many instances the orientation of the precursor at the water interface is largely preserved after transfer of the monolayer. The roughness and the thickness of the multilayers were determined by small-angle X-ray reflection.

Asthmatics have elevated levels of IL-17A compared to healthy controls. IL-17A is likely to contribute to reduced corticosteroid sensitivity of human airway epithelium. Here, we aimed to investigate the mechanistic underpinnings of this reduced sensitivity in more detail. Differentiated primary human airway epithelial cells (hAECs) were exposed to IL-17A in the absence or presence of dexamethasone. Cells were then collected for RNA sequencing analysis or used for barrier function experiments. Mucus was collected for volume measurement and basal medium for cytokine analysis. 2861 genes were differentially expressed by IL-17A (Padj < 0.05), of which the majority was not sensitive to dexamethasone (< 50% inhibition). IL-17A did inhibit canonical corticosteroid genes, such as HSD11B2 and FKBP5 (p < 0.05). Inflammatory and goblet cell metaplasia markers, cytokine secretion and mucus production were all induced by IL-17A, and these effects were not prevented by dexamethasone. Dexamethasone did reverse IL-17A-stimulated epithelial barrier disruption, and this was associated with gene expression changes related to cilia function and development. We conclude that IL-17A induces function-specific corticosteroid-insensitivity. Whereas inflammatory response genes and mucus production in primary hAECs in response to IL-17A were corticosteroid-insensitive, corticosteroids were able to reverse IL-17A-induced epithelial barrier disruption.

Asthmatics have elevated levels of IL-17A compared to healthy controls. IL-17A is likely to contribute to reduced corticosteroid sensitivity of human airway epithelium. Here, we aimed to investigate the mechanistic underpinnings of this reduced sensitivity in more detail. Differentiated primary human airway epithelial cells (hAECs) were exposed to IL-17A in the absence or presence of dexamethasone. Cells were then collected for RNA sequencing analysis or used for barrier function experiments. Mucus was collected for volume measurement and basal medium for cytokine analysis. 2861 genes were differentially expressed by IL-17A (Padj < 0.05), of which the majority was not sensitive to dexamethasone (< 50% inhibition). IL-17A did inhibit canonical corticosteroid genes, such as HSD11B2 and FKBP5 (p < 0.05). Inflammatory and goblet cell metaplasia markers, cytokine secretion and mucus production were all induced by IL-17A, and these effects were not prevented by dexamethasone. Dexamethasone did reverse IL-17A-stimulated epithelial barrier disruption, and this was associated with gene expression changes related to cilia function and development. We conclude that IL-17A induces function-specific corticosteroid-insensitivity. Whereas inflammatory response genes and mucus production in primary hAECs in response to IL-17A were corticosteroid-insensitive, corticosteroids were able to reverse IL-17A-induced epithelial barrier disruption.